16 clues contain a thematic item as an extra word. The remainder
fall into two groups (designated A and B), with two clues belonging
to both. Group A clues each contain an extra letter, to be removed
before solving; Group B clues each give an answer too short for its
space (in brackets).
5d Choirmaster repeatedly barred changes shift (7) SI?AR?? probably a type B clue
18d Nasty end for thug (7) ?????E? possibly type B?
Thank you both. I am now puzzling on the endgame. Which is the other feature that i insert in the 16 empty cells .....his monogram or the magic square? (or something else??)
The end game became tedious once you've worked out where all the gaps are. And that the normally useful "spells out the name of.." etc is that the missing letters anagrammatise work and creator.