Roger,
Thanks for your efforts. You might guess I have trawled the web so I have seen those you suggest but not yet found anything which fits the bill exactly.
If I do eventually go down this type of route I shall be more inclined to go for a mechanical (clockwork) unit rather than an electrical or electronic one. (I have had a number of clockwork units on previous cars and always found them reliable).
In the meantime, I have fitted a temporary two-way “flick” switch so I can indicate manually and ordered some nichrome wire to see if I can breathe life back into my unit. Trouble us my eyesight ain’t what it was so I may be struggling on that front. Hey-ho, say larvae!
Thanks again for your kind help,
B……..