The LNER A3 Class is a type of steam locomotive designed for the London and North Eastern Railway in the early 20th century. Known for their speed and efficiency, these locomotives were primarily used for express passenger services. The A3 Class was an evolution of the earlier A1 Class, featuring improved design and performance. One of the most famous A3 locomotives is Flying Scotsman, which became an iconic symbol of British rail travel. The A3 Class locomotives were built between 1922 and 1935, with a total of 70 units produced. They played a significant role in the development of high-speed rail travel in the UK.