InterCity 125

The InterCity 125 was the brand name of British Rail's High Speed Train (HST) fleet, introduced in 1976. The InterCity 125 train is made up of two power cars, one at each end of a fixed formation of Mark 3 carriages (the number of carriages varies by operator). The train operates at speeds of up to 125 mi/h in regular service, and has an absolute maximum speed of 148 mi/h, making it the fastest diesel-powered train in the world, a record it has held from introduction to the present day. Initially the sets were classified as Classes 253 and 254. A variant of the power cars operates in Australia as part of the XPT.

After three decades, the majority of the HST fleet is still in front-line revenue service under privatisation, and while the InterCity 125 brand name is rarely mentioned officially by the private train-operating companies (TOCs), the InterCity 125 still forms the backbone of intercity services on several British main lines. Most are expected to be replaced within the next 10 years by the Intercity Express Programme, but a number will continue in use on London to Devon/Cornwall services, where there are no plans to electrify the lines. Engineers from the companies responsible have calculated that, with a certain amount of rewiring, the Mark 3 carriages used can be made to last until at least 2035.

The power cars now have new engines and new lights, and the coaches have been refurbished. The trains currently operate out of London Paddington, St Pancras and King's Cross stations to Penzance, Plymouth, Newquay (summer), Paignton, Exeter, Taunton, Westbury, Oxford, Cardiff, Swansea, Carmarthen, Pembroke Dock (summer), Aberdeen, Bristol, Weston-super-Mare, Inverness, Harrogate, Hull, Nottingham, Sunderland, Leeds, Worcester, Great Malvern, Hereford and Cheltenham, as well as Summer services from the Scottish Lowlands and Newcastle to Newquay and Paignton, from Manchester to Penzance and Newquay and from Derby to Skegness, services from the Scottish Lowlands to Plymouth and Penzance and from Leeds to Aberdeen. One has also seen departmental use, as Network Rail's New Measurement Train, converted and in use since 2003.

Background
In the later 1950s and early 1960s, the British Transport Commission was modernising its rail network. In particular, it wanted to increase intercity speeds, so that the railways could compete more effectively with the new motorways. The government was unwilling to fund new railways, so the BTC focused its attention on increasing line speeds through the development of new trains and minor modifications to the existing infrastructure. A team of engineers was assembled at the Railway Technical Centre in Derby in the early 1960s, with the aim of developing an "Advanced Passenger Train" (APT), that would be capable of at least 125 mph and incorporate many features not previously seen on British railways—such as tilting to allow higher speeds on bends.

The APT project had suffered repeated delays, and in 1970, the British Railways Board (BRB) decided that it was not sufficiently developed to be able to provide modernisation of the railways in the short term. Thus, the BRB authorised the development of a high-speed diesel train, an operational prototype of which was to be built by 1972, for short-term use until the APT was able to take over.

Prototype
The prototype high-speed diesel train, which was to become the InterCity 125, was to be formed of a rake of passenger coaches sandwiched between two power cars—one at each end. The decision to use two power cars was taken very early in the project—engineers had calculated that the train would need 4,500 horsepower to sustain the required speed of 125 miles per hour on the routes for which it was being designed (the Great Western Main Line, Midland Main Line, and the Cross Country Route), and it was quickly established that no single "off-the-shelf" diesel engine was capable of producing such power. Also a factor in the decision was that the use of two locomotives, operating in push–pull formation, would cause less wear on the rails than a single, much heavier, locomotive. The framework of the new locomotive, classified British Rail Class 41, was built at Crewe Works before being transferred to Derby Carriage and Wagon Works for completion. The design of the locomotive incorporated a driving desk fitted around the driver, a sound-proofed door between the cab and the engine room, and, unusually, no side windows. The prototype became the first diesel locomotive in British railway history to use AC alternators in place of a DC generator, with the output converted to DC when used for traction.

The prototype train of seven coaches and two locomotives was completed in August 1972. By the autumn it was running trials on the main line and in May 1973 the prototype, now designated Class 252, set a world diesel speed record of 143.2 mph. The concept was proven in trial running between 1973 and 1976, and British Rail decided to build 27 production HSTs to transform InterCity services between London Paddington, Bristol, and South Wales.

Production versions
The first production power car, numbered 43002, was delivered in late 1975, with a significantly different appearance from the prototype. The streamlined front end lacked conventional buffers, and the drawgear was hidden under a cowling. The single cab front window was much larger than the prototype's, and side windows were included. There was also no driving position at the inner end.

The appearance of the train is the work of British designer Kenneth Grange. Grange was initially approached just to design the livery for the train, but under his own impetus decided to redesign the body, working with aerodynamics engineers. He went on to present the new design to British Rail and persuade them to adopt it.

An InterCity 125 consists of two Class 43 diesel-electric power cars, each powered originally by 2,250 bhp (1,678 kW) Paxman Valenta engines (although they have since been fitted with different engines), and a set of Mark 3 coaches (typically 7 or 8). Normally there are two types of HST sets, 8+2 (5 standard class, 1 buffet, 2 first class) and 7+2 (4 standard class, 1 buffet, 2 first class), where the +2 refers to the power cars at each end of the rake.

Key features of the design are the high power-to-weight ratio of the locomotives (1678 kW per ~70-tonne loco), which were purpose-built for high-speed passenger travel, improved crashworthiness over previous models, and bi-directional running avoiding the need for a locomotive to run around at terminating stations. Until the HST's introduction, the maximum speed of British trains was limited to 100 mph (160 km/h). The HST allowed a 25% increase in service speeds along many lines they operated.

The lighter axle loading allowed the trains to travel faster than conventional services along lines not suited to full-speed running, such as the Edinburgh to Aberdeen line. Known as HST differential speeds, coupled with superior acceleration capability over older locomotives, this allowed substantial cuts in journey times over these lines. The increased speed and rapid acceleration and deceleration of the HST made it ideal for passenger use.

Introduction into service
Deliveries continued through 1976, and in October a partial service of HSTs running at 125 mi/h began on the Western Region. A radical update of the standard BR livery on the power cars was complemented by the 'Inter-City 125' branding, which also appeared on timetables and promotional literature. By the start of the summer timetable in May 1977, the full complement of 27 Class 253 sets (253001 – 253027) was in service on the Western Region, completely replacing locomotive-hauled trains on the Bristol and South Wales routes. Passenger volumes on the trains rapidly increased due to the speed and frequency of the service, an effect previously seen only when electric trains had replaced diesel or steam services. The displacement by HSTs of the British Rail Class 50 locomotives to slower services effectively finished off the last 'Western' diesel-hydraulics Class 52 by early 1977. The production of Class 254 continued through 1977 for East Coast Main Line services. Initially, British Rail planned to fit uprated 2500 bhp Valenta engines to these longer HSTs, but this plan was shelved as the intensive running on the Western Region began to result in a high level of engine failures, often due to inadequate cooling; for a while, the WR power cars were derated to 2000 bhp. The Class 254s began to work important ECML expresses such as the Flying Scotsman from the summer timetable in May 1978. Within a year they had displaced the Deltics to lesser workings and reduced the London-Edinburgh journey time by up to an hour.

Production of HSTs continued until 1982, allowing them to take over services from London to the West Country, on the Cross Country Route and latterly on the Midland Main Line, serving destinations such as London, Bristol, Edinburgh, as far south as Penzance and as far north as Aberdeen and Inverness. Ninety-five HST sets, including 197 Class 43 powercars, were built between 1976 and 1982. More Mark 3 trailer cars were built in the 1980s for the Western Region Class 253s, making them eight-car rakes in common with those used on East Coast and Midland Main Line services. During the 1990s only the Cross-Country sets remained as seven-car rakes, with just one first-class carriage.

Not only did the HST bring considerable improvements in service on the railways, British Rail entered a period of active marketing which accompanied and supported the train's introduction. The Intercity service overall had become a vast success for British Rail.

World records
The prototype InterCity 125 (power cars 43000 and 43001) set the world record for diesel traction at 143.2 mph on 12 June 1973. An HST also holds the world speed record for a diesel train carrying passengers. On 27 September 1985, a special press run for the launch of a new Tees-Tyne Pullman service from Newcastle to London King's Cross, formed of a shortened 2+5 set, briefly touched 144 mi/h north of York. The world record for the fastest diesel-powered train, a speed of 148 mph, was set by an HST on 1 November 1987, while descending Stoke Bank with a test run for a new type of bogie, later to be used under the Mark 4 coaches used on the same route.

South West England and South Wales
On Western Region, InterCity 125 trains (designated class 253) were introduced initially for all services from London to Bristol and South Wales, and then extended for most day-time services from London to Devon and Cornwall. Some South Wales services were extended to Milford Haven, Fishguard and Pembroke in West Wales. From introduction, maintenance has always been provided from Old Oak Common and St Philip's Marsh, with Laira also carrying out maintenance once services to Devon and Cornwall were introduced in 1979.

The Class 47 locomotives still operated the cross-country services from Cornwall and South Wales to the North-East via the Cross Country Route, as well as London to the Midlands/Welsh Marches. However, Class 43s also replaced these services once the third batch of power cars was delivered. All these HSTs consisted of a 2+8 formation, normally with two first class coaches, a buffet car, and five second class coaches, all sandwiched between two power cars. Great Western Trains was formed out of the privatisation of British Rail and operated the InterCity routes from London Paddington to the west of England. In 1998 FirstGroup acquired Great Western Trains and rebranded it First Great Western. InterCity 125s continued to work the same diagrams they had under British Rail, albeit in a different livery.

First Great Western uses its large fleet of 43 HST sets to operate most intercity services from Paddington to Bristol, Bath, Chippenham, Swindon, Cardiff, Swansea, Carmarthen, Cheltenham Spa, Oxford, Worcester, Hereford, Paignton, Plymouth and Penzance, as well as some commuter services to Westbury, Taunton and Exeter St Davids. As of 2012 all First Great Western's intercity services are worked by InterCity 125 sets with the exception of sleeper services and certain Cotswold Line services.

From 2005 the First Great Western HSTs were re-engined with MTU power units, while at the same time the coaches were refurbished. Units for services in the M4 corridor/Thames Valley to Bristol, Hereford, Oxford, Exeter and Cardiff were converted into a high-density layout of mostly airline-style seats (only two tables per coach). This was in order to provide more seats for commuters. The remainder (for the routes to Swansea and the West Country) kept the tables.

The refurbished coaches have new seating (leather in first class), at-seat power points and a redesigned buffet bar. Some standard class carriages now have a Volo TV system.

Eastern England / Scotland
On the East Coast Main Line, the InterCity 125 designated Class 254 was the staple stock from the retirement of the Class 55 Deltic locomotives in 1980–1982 to the introduction of the InterCity 225 following electrification in 1990. They were concentrated on services from London King's Cross to Newcastle and Edinburgh Waverley with some extending to Glasgow Queen Street, Inverness and Aberdeen. In the months following the Penmanshiel Tunnel collapse in 1979, London to Scotland services ran via the Tyne Valley Line from Newcastle to Carlisle then on to Scotland via the West Coast Main Line. HSTs were also used on some services from London to Leeds, Bradford Forster Square, Cleethorpes, Hull and Scarborough.

The basic East Coast (ECML) formation was originally 2 + 8, increased to 2 + 9 in 2002 when extra stock became available. The ECML formation is nominally two first-class coaches, one buffet (with further 1st Class seating) and five (later six) standard-class coaches, sandwiched between the buffet and power cars.

For a few years, formations included a TRUK (trailer restaurant kitchen) and buffet car, many formations being 4 × TS, TRUK, Buffet, 2 × TF. Nine trailer car units followed this formation, with the addition of a TS. 'Pullman' services replace a TS with an additional first-class coach.

After privatisation, InterCity sets were operated by GNER, alongside electric InterCity 225 units from London to Newcastle and Edinburgh, as well as beyond the electrified sections (or where British Rail Class 91s cannot operate due to route availability restrictions) such as services to Hull, Skipton, Harrogate, Inverness and Aberdeen.

In January 2007 the first of GNER's 13 refurbished HSTs was unveiled, with the coaches rebuilt to the same 'Mallard' standard as its InterCity 225 electric sets with similar seating, lighting, carpets and buffet cars. Members of this fleet which have been refurbished have had '200' added to their original numbers. The power cars were upgraded with MTU engines. The first of the HST Mallards was in service by spring 2007. In 2007 the franchise was taken over by National Express East Coast, which continued the re-engining programme begun by GNER, and completed the refurbishment of the fleet in March 2009. Two power cars were transferred to First Great Western early in 2009. The final Mallard-upgraded Mark 3 coaches entered service with NXEC in October 2009.

Following an announcement by the National Express Group that it refused to provide further financial support to its subsidiary National Express East Coast, the NXEC franchise ceased on 13 November 2009, and the operation of the route returned to public ownership. As a result the 13 sets are now operated by Department of Transport operator East Coast (as of late 2009). East Coast introduced a new InterCity 125 service to Lincoln in 2011. The InterCity 125 was replaced by the electric InterCity 225 on the line to Skipton when the electrical infrastructure was upgraded. In total, 8 East Coast services per day in each direction use the InterCity 125.

In 2006, Grand Central Railway obtained six Class 43 power cars to operate its London-Sunderland passenger service via the East Coast Main Line. The service was due to begin in December 2006 although upgrade work to enable the coaching stock (which was formerly used for locomotive-hauled services and has a different electric heating/power supply system) to operate with Class 43 power cars was heavily delayed and therefore pushed the starting date back to 18 December 2007. HSTs 43084 and 43123 were the final operational Paxman Valenta power cars, being re-engined in 2010 with the MTU treatment. While at the works being re-engined, Grand Central added the orange stripe that appears on their Class 180 units, re-painted the front ends (this making them look more like the non-buffered HSTs), and re-numbered the power cars into the four-hundreds. These are the current numbers: 43465 (065)/467 (067)/468 (068)/480 (080)/484 (084)/423 (123). The re-numbering of 43123 was confusing to some enthusiasts, as they sometimes believed it was originally 43023 because 400 was added to the numbers of the other power cars, yet only 300 to this particular power car.

Midland Region
On London Midland Region, InterCity 125 trains were introduced later than on the other regions. They initially appeared on the former Midland Railway route from London St. Pancras to Sheffield and Nottingham. Although they were initially not permitted to exceed 100 mi/h on any part of the route, they still delivered time savings compared with the loco-hauled trains they replaced.

The Midland Main Line received a series of speed improvements over the next two decades, until it became possible for HSTs to run at up to 110 mi/h on some sections. An upgrade to the full 125 mi/h was proposed by British Rail in the early 1990s, but because of privatisation this did not happen.

Most long-distance services on this route have been transferred to new Class 222 Meridian diesel-electric multiple units, although many London services from Nottingham still use the InterCity 125, as do all services from London St Pancras to Leeds. Members of this fleet are currently being re-painted at the company’s Neville Hill Depot in Leeds; they have been refurbished with a different power unit to FGW and NXEC sets and are retaining their original numbers.

Midland Mainline inherited HSTs from BR after privatisation and operated them on its primary services at up to 110 mph.

43089 also was returned to work on the mainline after being used in an experimental programme conducted by Network Rail and Hitachi.

As of 2009, 26 are in service with East Midlands Trains. Since December 2013, InterCity 125 sets have been permitted to operate at speeds of up to 125 mph on certain parts of the routes from London St Pancras to Leeds and Nottingham.

Cross-Country Route
Post privatisation the Cross-Country Route was operated by Virgin Trains, who replaced the InterCity 125 trains in the period 2002–2004 with Voyager high-speed DMUs.

The majority of the former Virgin Cross Country fleet went into storage for several years but a small number moved to Midland Mainline to supplement its fleet.

In the 2007 the franchise passed to Cross Country (an Arriva Trains subsidiary). Because of overcrowding, Cross Country reintroduced five HSTs to supplement its Voyagers. In late September 2008 Cross Country refurbished its first HST set. The coaches have been refurbished to a similar "Mallard" standard as GNER trains, though their interior is in burgundy and there are fewer tables. They also differ from the East Coast sets by having electronic seat reservations, and the buffet car has been removed, with all catering provided at-seat from a catering base in coach B. Most of the carriages are rebuilt from loco-hauled Mark 3s. The refurbishment was carried out by Wabtec, Doncaster Works.

Each set has had a TS removed (now 2 power cars + 7 coaches). Four sets are now back in daily use again since December 2010, after only two sets were used in service (three on Mondays and Fridays) for a while in 2010. No explanation was provided for the sudden reduction in fleet usage.

CrossCountry operates HSTs to the following destinations:


 * Plymouth
 * Leeds
 * Edinburgh
 * Dundee
 * Glasgow
 * Newquay (summer weekends only)
 * Penzance
 * Paignton (summer weekends only)

West Coast and North Wales
Virgin Trains HSTs regularly worked out of London Euston and Birmingham International to Holyhead and Blackpool North, until they were re-deployed in May 2004. Due to there being numerous curves on the West Coast Main Line, the trains were not permitted to exceed 100 mph on any part of the route.

When the West Coast Main Line was upgraded by Network Rail in the 2000s, it became necessary to operate diversionary routes whilst work was going on. As a result Midland Mainline was asked by the then Strategic Rail Authority (SRA) to operate services between London and Manchester via the Midland Main Line and Hope Valley Line into London St Pancras while West Coast Main Line renovation works took place. In a temporary operation dubbed Project Rio, a large percentage of the stored Virgin Cross-Country power cars were overhauled and returned to service in an enlarged Midland Mainline fleet. Ending on 10 September 2004, the Project Rio fleet was gradually disbanded, with power cars moving to First Great Western, GNER or CrossCountry.

Network Rail
One HST set is in service with Network Rail, painted in departmental yellow, and often referred to as the "flying banana" (a nickname that was originally applied to the whole class because when first introduced by BR they wore a predominantly yellow livery). The set is the New Measurement Train.

Another single engine, 43089, was used in tests on hybrid battery powered vehicles in collaboration with Hitachi. It has since been returned to normal service with East Midlands Trains.

Numbering and formation
When Crewe Works built them, the InterCity 125 units were considered to be diesel multiple units, and were allocated British Rail Class 253 and Class 254 for Western and Eastern Region services respectively.

British Rail considered the HST, a fixed formation train with a locomotive at each end, as a multiple unit on introduction, and numbered them as such: 253 xxx (Western Region) and 254 xxx (Eastern and Scottish Regions). However, because two power cars carried the same 'set number', problems arose when, for servicing reasons, different units were used on a train, which would then display a different number at each end. For this reason, British Rail abolished the initial numbering system and all individual power cars became identified as such, using the format 43 xxx - this number was previously carried in small digits in the bodysides, prefixed by a 'W' for Western, 'E' for Eastern or 'Sc' for Scottish to identify the region, thus the power cars were reclassified as Class 43 diesel locomotives.

The vehicle types used to form High Speed Trains are listed below:

The 197 power cars produced are numbered 43002-43198. 43001 was applied to the second of the two prototype power cars, while the first of the pair (now preserved at York) became 43000 - unusual because BR TOPS classification numbered its locomotives from 001 upwards (this was because it was not, at the time, classified as a locomotive).

In 2002, Class 255 was allocated for the reformation of some HST power cars and trailers into semi-fixed formation trains, to be known as Virgin Challenger units, for use by Virgin Trains. These formations would have had power cars sandwiching one Trailer First, a Trailer Buffet, two Trailer Seconds and a Trailer Guard Second. These plans came to naught as the Strategic Rail Authority planned to transfer most of the stock to Midland Mainline for its 'Rio' services between London and Manchester.

Livery




The original "Inter-City 125" livery was blue and grey, with a yellow front to improve visibility which continued down the side of the power cars. This was the livery recorded in British Rail's corporate identity manual of August 1977.

The second livery had mostly grey power-cars with a white band along the middle, yellow underneath the white band, with the InterCity colours (cream, red, white, brown) for the parcel compartment of the power cars and the coaches.

There was brownish-grey, dark grey (almost black) around the windows with a red and white stripe below the windows, and retaining the yellow bands on the power cars. The final variant of this livery saw the yellow side-bands replaced with white and did not feature the British Rail name or logo: it carried the new sector branding Intercity logo in serif type and an image of a flying swallow. This is commonly referred to as "InterCity Swallow" livery, and was applied to other locomotives in the sector.

After the privatisation of British Rail, train operating companies painted the HSTs in their own colour schemes, with some lasting longer than others.

Public reaction
The Intercity service proved an instant hit with the British public. By the early 1980s the HST had caught the travelling public's imagination, thanks in part to a television advertising campaign fronted by Jimmy Savile, together with the advertising strap-line "This Is The Age Of The Train". British Rail enjoyed a boom in patronage on the routes operated by the HSTs, and InterCity's profits jumped accordingly, with cross-subsidisation safeguarding the future of rural routes that had been under threat of closure since the Beeching Axe of the 1960s.

International attention
The success of the HST has had significant international impact. Foreign press for decades observed and praised the speed and quality of the service. It ranks as the world's second high-speed commercial passenger service, after Japan's Shinkansen, which first connected Tokyo and Osaka on 1 October 1964.

The InterCity 125 was used as a case study for evaluating the potential for a high-speed rail system in California. In Australia, the HST was used as the base for developing the XPT, in cooperation with British Rail.

Scale models
There have been many model and toy guises of the IC125. One of the first in the UK was by Hornby Railways, which launched its first model version in 1977. This model was supplied with an incorrect length Mk3 coach which was shortened to allow the model to reliably negotiate the smallest radius curves. This was done by removing one of the 8 side windows rather than scaling the whole length. It was later released in InterCity 'Swallow' livery, Great Western green-and-white, Midland Mainline and Virgin Trains. Lima released its version of the IC125 in 1982, of which the Mark 3 coaches were correct to the lengths of the real-life coaches and included the Guard's coach. Hornby eventually followed suit in the late-1990s, when its short Mark 3 coaches were replaced by correct scale length ones but omitted the Guard's coach. Hornby released a totally new version of the InterCity 125 power cars in late 2008. Dapol produce an N gauge model of the train. Railway Shop (Hong Kong) produces a T gauge model (1:450 scale).

Damaged vehicles and accidents
Three Class 43 locomotives have been written off in railway accidents, all of which occurred on the Great Western Main Line. 43011 was written off in the Ladbroke Grove rail crash, 43019 was written off after the Ufton Nervet rail crash, and 43173 was scrapped at Pig's Bay in Essex after heavy damage in the Southall rail crash. In all cases, the damage was to the leading power car - the trailing end power cars at the other end of the HST set suffered only limited or no damage, and were returned to service. At Ladbroke Grove and Ufton Nervet the accidents were ultimately caused by factors not involving the HST sets or their drivers, although the set involved in the Ladbroke Grove crash had a faulty AWS system; however, the Southall accident was due to the HST and a Freight train, which was due to be entering Southall Goods Yard, at approximately 13.20 GMT, Crossing at an odd angle. The Signalling system had reverted the signals for the HST's route to danger. The immediate cause of the crash was the result of the driver of the HST passing a red signal without stopping. In addition, the leading power car of the set had a faulty Automatic Warning System which if operational would have alerted the driver to his error and possibly prevented the accident. Following investigation, this system has since been required to be kept operational and switched on for all use of the Intercity 125 fleet.

Re-engining and refurbishment


In 2005, the train leasing company, Angel Trains, initiated and led an industry-wide programme to replace the 30-year old Paxman Valenta engines in the HST power cars with new MTU 16V 4000 engines. The upgrade, which was part of a £110 million total investment made by Angel Trains on its fleet of High Speed Trains, included the re-powering and refurbishment of 54 HST power cars, then on lease to GNER (now East Coast) (23), First Great Western (26) and CrossCountry (5). Virgin Trains planned a similar project in the early 2000s, but with the collapse of the programme the upgraded trainsets were sold along with their unupgraded stablemates.

Additionally many operators undertook some sort of reburbishment programme on the Mark 3 carriages in the early 2000s. With the long-term delay and change of direction of the HST2 programme, operators began to refurbish their HST fleets in 2006 - both by remotoring with the more modern MTU4000 diesel engine, and by refurbishing the carriage interiors. It is anticipated that these overhauls will give the HST at least another 10 years in front-line service.

Replacements
The first partial replacement of HSTs occurred from 1988 on the East Coast Main Line, with the introduction of the InterCity 225 when the line to Edinburgh was electrified. Some were retained for services to Aberdeen, Inverness, Skipton, Bradford and Hull.

As the Intercity 125 fleet has become old compared to most stock used in passenger service it has been recognised that it is near the end of its service life. More recently HSTs have been replaced (or augmented) by high-speed DMUs such as the Voyagers and the UK express version of Alstom's Coradia.

These new DMUs have better acceleration than the HST due to a higher power/weight ratio, with greater efficiency and braking performance in addition. However passenger comfort is reduced due to the vibrations and noise caused by the underfloor engines, compared to the much quieter Mark 3 coaches.

In 2005 the initial concept of HST2 was rejected by the government and the rail industry as a like-for-like replacement for the HST fleet. In the light of this rejection, in 2006 existing operators turned to refurbishments of the Intercity 125 trains.

Nevertheless, HST2 has been expanded and replaced by the Intercity Express Programme, with proposals for a joint replacement of both HST and Intercity 225 trains. The likely successor to the two Intercity trains is the Hitachi Super Express, which has emerged as the preferred bidder.

On the Greater Western franchise, the current fleet of HSTs is expected to remain in service until 2017, the scheduled date for introduction of the Intercity Express. Between 12 and 20 HST sets will then be retained and refurbished to carry on providing services between London and Devon and Cornwall, where no electrification is planned, through to the mid-2020s. A 2011 report concluded that the Mark 3 coaches could remain in service as late as 2035 with some minor rewiring and enhancements required under disability legislation.

Sewage discharge
Legally in the UK, train operators are allowed to discharge 5 impgal of sewage per carriage per journey, on to the railtrack. Most Mk3 carriages have only holding tanks, not fully compliant toilet tanks. However, in the 2000s both the RMT trade union and politicians were concerned at the environmental impact of this legacy issue. The problem was first raised in 2003 after Railtrack staff at Nottingham abandoned local clean-up and then track maintenance procedures due to an excessive built up of sewage waste in the area. In 2006 the RMT agreed waste-tank and clean-out developments at Northern Rail's Heaton depot in 2006 with GNER, plus new clean-out procedures at all other depots, to solve an ongoing dispute over the previous 18 months. By 2011, the European Union had started a formal investigation to see whether trains composed of such carriages were breaking EU environmental and health laws, although the Environment Agency confirmed that train companies claimed special exemptions to dump waste along the tracks. In 2013, Transport Minister Susan Kramer branded the practice "utterly disgusting" and called on the industry to take action. ATOC responded by stating that, as all new vehicles had to be fitted with compliant toilet tanks, with withdrawal of the HSTs by the end of 2017 the problem would be solved.

Named trains
The InterCity 125 is used for the following named trains:


 * Armada
 * Atlantic Coast Express
 * Bristolian
 * Capitals United
 * Cathedrals Express
 * Cheltenham Spa Express
 * Cornishman
 * Cornish Riviera
 * Devon Express
 * Golden Hind
 * Highland Chieftain
 * Hull Executive
 * Mayflower
 * Merchant Venturer
 * Northern Lights
 * Pembroke Coast Express
 * Red Dragon
 * Robin Hood
 * Royal Duchy
 * Saint David
 * Torbay Express