I can tell you a little about JWS and machines made by this company in the 1960s.
My dad, John ("Jack") William Stickley, owned and operated the JWS factory in Thundersley, near Southend. I was born in 1961, so I don't remember much directly, but I do have some photos that I can scan and post if anyone's interested. His main income came from assembling fruit machines, that, I believe, also had the JWS logo pressed into them. I don't know about his business arrangements, but I assume he assembled and tested them for a bigger company.
He did love designing and building arcade machines like Push 'Em Off, Treasure Cave and Moon Patrol. This all happened in the 1960s, when in particular I couldn't tell you, except it was probably earlier rather than later.
I know he was at the forefront with his penny pusher, as, I believe it was the first one to be installed in Southend's arcades. I know this due to a story he used to tell: Dad had built and tested the machine in the factory, but had no idea how it would perform in a live environment. He convinced one arcade owner to trial it, however, later the same day he received a call to say the machine had made a loud noise although it still seemed to be functioning OK. When dad checked it out, the coin box had completely filled and the weight had broken its supports. Successful then and still successful I believe.