The smallest armored train ever built, shot down German aircraft during World War 2. A 1/3rd scale steam locomotive clad in boiler plate, armed with WWI-era Lewis guns and anti-tank rifles, crewed by 7 soldiers, was conceived and built in the 1920s by millionaire racing car drivers

originally conceived and built in the 1920s by millionaire racing car drivers Captain Jack Howey and Count Louis Zborowski

Count Louis Zborowski had constructed a railway at Higham Park, his home at Bridge, Kent, and agreed to donate the rolling stock and infrastructure to the project. However, he was killed in a motor racing accident at the Monza Grand Prix on 19 October 1924 before the Romney Marsh site was chosen, and Howey continued the project alone.

https://en.wikipedia.org/wiki/Romney,_Hythe_and_Dymchurch_Railway 

https://iwmvolunteerlondon.wordpress.com/2020/10/14/a-little-about-a-little-armoured-train-the-romney-hythe-and-dymchurch-railway-1940

https://www.facebook.com/groups/132380976935515/posts/3486995978140648