September 1935: Class A4 locomotive enters service

Whilst the majority of the article (based on details supplied by the London and North Eastern Railway Company (LNER)) focusses on the Silver Jubilee train - launched to commemorate the 25-year reign of King George V (who died just four months later) - it is the the 2509 Silver Link, the locomotive that pulled it, which is of the greatest significance in engineering terms.

Designed by celebrated railway engineer Sir Nigel Gresley, Silver Link was the first of the Class A4 locomotives, a futuristic-looking family of engines that remain Britain’s fastest ever class of steam locomotives.  The most famous member of this illustrious group was the 4468 Mallard, which just a couple of years later (July, 1938) famously reached a world-record speed for a steam locomotive of 126mph.

The Class A4 locomotives were notable for a multitude of reasons. Internal streamlining to the steam circuit, a higher boiler pressure, and the inclusion of a combustion chamber in the fire box all played a part in its superior performance. But one of the key areas of innovation is also one of the most visible, a streamlined aerodynamically optimised design reportedly inspired by the racing cars of Ettore Bugatti.