In Great Britain, the Victorians built the vast bulk of the country’s railway system and   constructed steam locomotives to work them - many different designs were created, with many different results. The final form of the steam locomotive was seen in the designs introduced in the early years of the 20th century, from there on development was in detail and power.

Using footage from the last quarter of a century, this programme looks at the way this final form was refined by some of the most famous engineers of their time, right up to the last steam locomotives built for main line service in the country.

This is The Austerity Age, examining the last private locomotives.

The Second World War virtually brought steam locomotive development to a halt in Great Britain - the watchword became "Austerity", as engineers tried to produce simpler and cheaper designs.

This was the case everywhere except on the Southern Railway, where the mercurial Oliver Bulleid produced some of the most complicated and expensive steam locomotives ever to work on Britain’s railways. Elsewhere, the GWR continued on its own course, while the LMS produced a series of efficient smaller types to work almost anywhere. Gresley’s sewing-machine engineering was swept aside by Thompson’s simple designs on the LNER and even the Government got in on the act by specifying special "Austerity" designs for the use of the WD, or War Department.