@Don McErlean I can show you pictures of my British Marx 3978 Locos I already have here ... a black clockwork , and a blue electric set .
Marx opened a British factory in 1937, not great timing , but handy for the Brits as it was converted in the war , like most toy companies, into supplying goods for the war effort ... after the war they reverted back to making toys for the UK market
After the war production went back into making toys 
They opened another factory in Swansea in South Wales and I believe this is where the later trains were made although I am sure I read somewhere they started production around 1947 at the older Dudley Works ... here is an ad for Spain by them in 1949
They definitely made other cast trains at Dudley however both proir to and after the war .
Binns road linky http://www.binnsroad.co.uk/railways/marx/british/
SO here are a few pics of the British Marx 3978's I already have in the collection
Clockwork Black loco
And Electric Blue version ...
