There were political as well as practical reasons behind the resistance to dieselisation in particular: the Labour Government of Clement Attlee did not want to significantly reduce the demand for domestically produced coal in favour of imported oil, thus both affecting the balance of payments and potentially causing unemployment.
Robin Riddles, who was effectively the British Railways' Chief Mechanical Engineer, disagreed with the dieselisation programme, arguing that it would be too expensive to import oil given the large amounts of domestically available coal.
In 1951, the British Transport Commission approved a new series of standard locomotives and coaches incorporating design features primarily from the London, Midland & Scottish Railway but also the other pre-nationalisation companies.
By the middle of the decade, however, it was clear that British Railways were in trouble, particularly in the freight haulage business to which they were losing ground to road and air traffic (the latter thanks to a postwar glut of available transport aircraft).
The aim was to increase speed, reliability, safety and line capacity, through a series of measures that would make services more attractive to passengers and freight operators, thus recovering traffic that was being lost to the roads.
[10] An attempt was made to simply update the railways as they already stood rather than reacting to changes in the way goods and people were travelling in the post-war years.
[11] Massive investments were made in marshalling yards at a time when the small wagonload traffic which they dealt with was in steep decline and being lost rapidly to the roads.
Although not laid out in the published Modernisation Plan, BR's initial approach to this huge acquisition task was to implement a pilot scheme, commissioning orders for 171 (later increased to 174) diesel locomotives from six independent manufacturers (due to currency and political considerations these were all British firms, even though several had little or no experience of diesel locomotive design and building) plus BR's own design offices and workshops.
The intention was that the most successful designs and elements proven by the pilot scheme would form the basis of the large-scale orders called for by the Modernisation Plan over the next decade.
However, this did not happen until the Transport Act 1962 gave BR freedom of contract, and until then the Modernisation Plan had to commission locomotives, rolling stock and facilities to manage the ever-declining but legally-required wagonload freight traffic.
The timing of the Modernisation Plan was also unfortunate, as just months after its publication the train drivers' trade union, ASLEF, called a strike that lasted for 17 days, causing major disruption to the network.
The modernisation of BR's freight-handling facilities was ineffective and even before the Plan was officially concluded, many of the large yards built a few years previously were mostly empty.
Former LMS lines in the south-west of the country, including the northern section of the Somerset and Dorset Joint Railway, were transferred to the Western region.
The new diesel locomotives, so troublesome during the Modernisation Plan years, were becoming more reliable and the closure of so many routes after the Beeching Report meant that the required fleet reduced significantly, and by the end of the 1960s, all the pre-nationalisation rolling stock had been replaced with the new standard patterns.
In the early 1960s yellow warning panels, now characteristic of British railways, were added to the fronts of diesel and electric locomotives and multiple units in order to increase the safety of track workers.
This re-branding introduced the double-arrow logo to represent the industry as a whole; the standardised Rail Alphabet typeface used for all communications and signs; and the BR blue livery, which was applied to nearly all locomotives and rolling stock.
The 1970s saw British Rail successfully introduce high speed diesel train services, as well as major resignalling projects designed to increase operational efficiency.
However, lack of money, political pressure and the launch of the prototype into passenger service before technical problems were fully overcome led to the project being cancelled in the early 1980s.
The InterCity 125 was planned as a stop gap measure, meant to fill until electrification was spread across all main lines and the Advanced Passenger Train (APT) was in service.
The HST applied what had been learned so far to traditional technology – a parallel project to the APT development, based on conventional principles but incorporating the newly discovered knowledge of wheel/rail interaction and suspension design.
The class holds the world record for diesel traction, achieving 148.4 mph (238 km/h) with a shortened set running speed trials between Darlington and York.
The HST was introduced from 1976 on the Great Western Main Line between London Paddington and Bristol Temple Meads/Swansea, at a time when the maximum speed of British trains was 100 mph (160 km/h).
[23] The objective of the tilt was to minimise the discomfort to passengers caused by taking the curves of the West Coast Main Line at high speed.
An attempt at a cheap DMU replacement was made with the Pacer—essentially a modified bus body mounted on a rigid 4-wheel freight wagon chassis—which met with customer dissatisfaction.
[30] At a regional level, Network SouthEast undertook numerous electrification projects, including the Midland Main Line to Bedford and the Southern 750 V DC system reached Hastings and Weymouth.
Thameslink, a service that connected the northern and southern halves of London's suburban network, was introduced via the re-opened Snow Hill tunnel in 1988.
In 1988, the Clapham Junction rail crash killed 35 people when three commuter trains collided, the worst railway accident in Britain in 30 years.
A contributing technical factor was the lack of double switching in the signal relay circuits, which would have prevented a single false feed causing an accident.
A follow on from the Chiltern Main Line upgrade was to be the nationwide roll-out of the Automatic Train Protection system, which helped prevent accidents caused by Signals Passed at Danger (SPADs).
A lack of resources also led to the cancellation during the planning stage of other major infrastructure refurbishment projects, including Crossrail, an east–west line through London which eventually opened in May 2022.