I’ve gone with that configuration, it really can’t be anything else. I doubt it’s TO because the quote is unequivocally said “about” the other person rather than “at” them. Agreed it’s rare that an element of the theme is left so vague.
Will37, the steer is concrete - but in still fluid Readimix form. The preamble uses both “on” (“…comment on a”) and “of” (“who spoke of whom”). Meanwhile, ODQ uses “of” (“of Y”). You pays your money and you takes your choice! The Spectator really could do with a crossword editor……😉
I opted for 'on' after some hesitation but given the ambiguity caused by the preamble surely they will have to accept either. At least they had the grace to print last week's missing clue.
Reading the rubric carefully indicates that Settee 1 is probably right to suggest 'of' for the two cells in the top row. Thanks Settee, are you sitting comfortably ?