The Bamford family includes J C Bamford, better known for the JCB machines that his company manufactures at Uttoxeter in the UK.
The engine side goes back to the 1930's or so, they made small water petrol engines up to about 5hp, then they went into water cooled diesels, and their last product as a company was the AC1,2 and 3 series of small air-cooled engines.
The engine company is different than the JCB side of things, and Richard Bamford, who was the last of the old family, died a couple of years ago. He was always prepared to help with copies of manuals etc etc., very nice man.
The Z series diesels are big and heavy, they made a twin as well, all have a unique hinged crankcase so you can look at the crank and big end without draining the oil.
No spares available these days, but injection parts can be obtained.
Good engine, nothing specially good or bad, and relatively rare these days, worth a punt if it is near to you, but they are HEAVY!
Peter