The British Rail

British Rail

British Railways , which from 1965 traded as British Rail, was the operator of most of the rail transport in Great Britain between 1948 and 1997. It was formed from the nationalisation of the "Big Four" British railway companies and lasted until the gradual privatisation of British Rail, in stages...

 Class 43 (HST) is the TOPS

TOPS

Total Operations Processing System, or TOPS, is a computer system for managing the locomotives and rolling stock owned by a rail system...

 classification used for the InterCity 125

InterCity 125

The InterCity 125 was the brand name of British Rail's High Speed Train fleet. The InterCity 125 train is made up of two power cars, one at each end of a fixed formation of Mark 3 carriages, and is capable of , making the train the fastest diesel-powered locomotive in regular service in the...

 High Speed Train power cars, built by BREL

BREL

British Rail Engineering Limited , was the railway systems engineering division of British Rail, until the design and building of trains in the UK was privatised in 1993. On 31 October 1969, the company was incorporated as British Rail Engineering Limited.-Main products:The vast majority of BREL's...

 from 1975 to 1982.

The class is the fastest diesel unit in the world, with an absolute maximum speed of 148 mi/h, and a regular service speed of 125 mi/h. There are claims that this diesel rail speed record has been broken twice unofficially: by a Russian train in 1992 achieving 168 mi/h, and a Spanish train reporting 254 kilometre per hour in 2002.
In the early 1970s the British Railways Board

British Railways Board

The British Railways Board was a nationalised industry in the United Kingdom that existed from 1962 to 2001. From its foundation until 1997, it was responsible for most railway services in Great Britain, trading under the brand names British Railways and, from 1965, British Rail...

 (BRB) decided to replace their main-line express diesel traction.