Mardens Perfect change machine

[pennymachines]

Anyone seen one of these early change machines before? Please tell us if you know anything about the origins/history/manufacturer etc. of this device.
It was recently acquired by a "well known collector" (no, not me, sadly). It seems to have been made in some volume but has anyone seen it before? It's cast iron (heavy!), 24" high, base about 9" square with brass tubes and cups.
Called Mardens Perfect it's not really a slot machine (sounds more like a real ale to me), although it has much in common with the cast iron gold changers by Avery, Garrett et al. Like a cash till, it would have been used in the presence of an attendant who would have operated the mechanism. You handed over your £1 bank note and received equal value in silver coinage delivered in the brass cup which was then returned to the machine.

What date would you guess? The Patent 158033 informs us it was filed in 1919. Looks more "old fashioned" doesn't it?

By the way, the European Patent Office Website now includes all the early British patents that previously had to be viewed on paper. Fantastic resource!