Hi Jeff thanks for the offer, I'm still battling with GILL and Triumph, both being very less than helpful.
GILL now admit they made some igniters for Hesketh after telling me they didn't, but that they are the same as the GP4 igniter they make for Triumph, but they won't sell me one because they are under obligation to only supply them to Triumph.
Triumph have told me that they use the GP4 igniter on some of their carburetted Bonneville range but won't tell me which ones, only that I can buy a new igniter from one of their stockists.
It's great to know that these companies can be so helpful