I’m late to this party. (House hunting - moving out of the countryside closer to a bus stop and shops to end our total car reliance. Offer on a cottage on the outskirts of the county town with a bus stop at the end of the road and the town centre shops in very reasonable walking distance accepted this afternoon. Hooray!) I enjoyed the challenge of the gridfill and have the name and the material from the missed/extra letters and the circled cells. So thank you for all that, Vismut. But I may leave the rest of the endgame which others have apparently found underwhelming and a tad confusing to concentrate on cracking a bottle of fizz.