Gilbert Lowen Hopwood

Gilbert Hopwood worked for his uncle Sir George Hume (pioneer of ticket printing and issuing machines) for Garrard in London with AEG (82 York Way). Gilbert was responsible for the first self serve ticket + change machines on London Underground. These were a little quirky and as a result earned him a cartoon in Punch magazine. The cartoon apparently showed him being showered with tickets from one of his machines with a caption like "Oh! Mr Hopwood". A couple of years before he died he recognised one of his machines in the Science Museum.

Croombe + Jacksons "Rails through the Clay" - 1st edition pg 384 indicates

experiments with AEG machines in Nov '26. The following is taken from a section from that page about coin operated ticket machines. "....Change giving was a problem which impeded development. Some use was made of staff whoses sole duty was to give change, and an elaborate passenger-operated change-giving machine was tried at various stations between 1932 and 1934. The solution lay in the combined ticket-and-change machine. This was first tried in November 1926 but was not wholly satisfactory and was withdrawn. In 1930 came the "bunch-hopper" machine which accepted combinations of copper coins all together, and printed the ticket from a plain roll on the same principle as a Rapid Printer. The earliest machines of this type were by AEG, but later examples were by Brecknell, Munro and Rodgers (today, Brecknell, Dolman and Rodgers)."

J.P.Thomas "Handling London's Underground Traffic" of 1928 pg's 160-163 seems to corroborate this, also has a nice picture of a "combined ticket-giving and change-giving machine...in use at Mansion House and other stations"