I have a different type of foot-change mechanism which does not use an index plate. It was fitted to a 1936 flyer which I bought a few years ago but which was not running so I cannot confirm whether it worked or not – I must assume that it did though. The gearbox fitted was an earlier hand-change type with this addition bolted through the gearbox front cover bolts in a similar fashion to the Scott/Velocette foot change mechanism. It is different from the Scott/Velocette type in that it has a larger barrel which clicks into various set (and quite rigid) positions rather than simply up and down.

If I get chance I will see if I can post a photograph.