Yes over the weekend a mate came round and we went through everything again. of all simple things, it was the coil. Even though I temporarily fitted a spare one that I had......Which also must be duff. I bought another new one which arrived Saturday and cured the problem.
Both the previous coils were delivering a spark, but obviously not strong enough. I've restarted the Tilly several times over the weekend and all seems fine now. Ron🤞