Picaroon doing double duty this weekend: also (as Buccaneer) in the FT puzzle published Friday night. I think he appears in that FT slot more often than as the Guardian Prize setter.
I'm not a fan of this grid since there is only 1 letter linking each corner to the rest of the grid. It was helped by the 2 clues in the middle providing letters in 2 quadrants though.
I can't parse 21A either (and I had the obvious wrong answer (Pauline) one at first).
Ah yeah, those kinds of spots, I see. I removed a K from a word meaning "to have a quick look" at first but that was not the correct tense, would have just been "spot" then.