From the BEEB

Been and Gone: The voice of the moon landings and the father of trainspotting

Railway enthusiast Ian Allan turned trainspotting into a multi-million pound business. It was while working as a clerk for the Southern Railway that he had the idea of publishing a book listing all the company’s locomotives. His managers failed to see the point so Allan published the ABC of Southern Railway Locomotives in 1942. Originally he had intended it to be a reference work and was amazed when schoolboys started appearing at the end of platforms, clutching his book and ticking off the engines as they passed by. He quickly produced volumes covering the other large railway companies as well as buses and trams. By 1962 he was running a thriving business, publishing books on all forms of transport. With the end of the steam era he became an active campaigner in the railway preservation movement, successfully persuading British Railways to reverse a decision to ban privately-owned steam engines from using their lines.

http://www.bbc.co.uk/news/magazine-33371524