Most of the major safe makers also produced other types of locks, sometimes for bank work and othertimes simply because they could and would tender for contracts. Milners are quite well known for producing locks for use on railways in South America !
I suspect this is a case in point, a railway wanted a certain design of lock made to a certain quality and Price won the contract.
As to value, not much as there is no benchmark to work from, although I suspect more of a curiosity than anything else. If it had been a fine brass padlock it would have been another matter as a fine padlock, in mint condition with two keys sold for well over a thousand pounds not too long ago !
