Rev counter? driven from the back end of the dynamo?

what about a shutter type of radiator blind ?

Tell you what I'm beginning to think: a very old, after-market rev-counter such as Ratbag has mentioned...? I'm sure I've come across something like this before, many years ago.

Think you are on to something there Tall Ratbag/Extreedoc,I have seen similar fittings on older tractors from 50's 60's.

Just remembered, some Triumphs used to have a tacho drive cable driven by an extra gear on the distributor drive shaft.

A rev counter is a possibility.... It does already have a large Jaeger rev counter in the other instrument hole to show engine revs, but I am wondering if this drive cable was for a rev counter for a dynamo or alternator? Reason I say that is that there is a large, long redundant, control box on the inner wing up near the dynamo and I am just wondering if it used to have a 2nd dynamo with rev counter for charging an auxiliary battery for a caravan (or similar) as there is also wiring to a trailer socket and switches for same..... It seems the mystery will not be easily solved. Ultimately these remains are now going to be removed....

In the meantime - starter button made (original was missing):-


Horn slip ring contact made (original had been bent and broken):-


Tex Magna indicator switch rebuilt with new rubber tyre:-


Yards of redundant wiring stripped out, progress on electrics, fuel tank drained, etc. etc. Moving on

Having now spent a coupe of years getting used to a TexMagna I think it is a marvel of ingenuity and engineering that today would be a bit of plastic that breaks or a micro chip.