Well, it may be a short lived fix, but I gave it half an hour this
morning with no earth, still alive by the way. Reconnected the earth
and no more tripping. Gave it another hour and then left it to cool
down. Tried it this evening and still no trip so OK for now. We'll see
how it goes after a few days in an unheated kitchen.

Thanks to everyone for all comments, a varied assortment and much
appreciated.
--
Bill