My father has had this electric shock machine for over 50 years.
He obtained it from a relative, when the bar it had been sitting for the patrons "amusement" closed.

It's started by dropping an old penny into the slot, you hold the round handle on the left, and attempt to turn the handle on the right from 0 to 100. As you turn, the electrical charge increases, causing initially a tingle that swells, causing an uncomfortable sensation that quickly turns into pain and arm contractions.

My dad modified it to run on a D size battery, but as he's now in his 90's he can't remember what the original battery looked like.

When I was very young, he attached one of the old giant batteries that you used to run Hornby railway sets, and I grabbed the handles before he could stop me. I had barely turned them and was utterly incapable of letting go, much to my horror and everyone else's amusement.

Does anyone know where they came from, who made them, where they were used or when?

Any information extremely gratefully accepted

Image of the contraption here, with a close up of the message encouraging you to try it, with some dubious health claims...