The MR-2 & 3 are of course the solution but this thing was supposed to be the generic ...which it is not. Have given up trying to work out what it is and have a MR-3 on its way. These Generic whatsits are on ebay as MR-x replacements and clearly they are not so maybe someone else will be able to use this advice when challenging a seller and one that says ...
GENERIC Soft Shutter Release USED MR-3 Type.
As pictured.
Works PERFECTLY.
For Nikon: N2000, N2020, F-301, F-501, N70, N8008s, F-801, F4s, MD-4, MD-11, MD-12, MD-15 ...
But all solved and if someone wants this 'thing' for the price of the post they can PM me.