Across
1 Circles rook with pieces following opponent’s opening (6)
4 Catch post in western extremity (5,3)
9 25 left by river (5)
10 What may be taught at school about helium, head of mathematics is to test (9)
11 Letter from Greece about a dance (7)
12 Spanish wine imbibed by river results in easing of tension (7)
13 Pretty sweet carton(9-3)
17 Dorset lighthouse seen in harbour - come ashore on account (8,4)
20 Le Carré novel, more readable (7)
21 Vessel’s gone out with everybody on board (7)
23 Cabins for the upwardly mobile? (5,4)
24 Quiet old character in trim (5)
25 Hanger-on ruined pair’s tea (8)
26 Want to change sides (6)
Down
1 Painting, superficially attractive, depicting ecological problem at sea (3,5)
2 Rodgers and Hart song, sad, second on (4,4)
3 Greek character volunteers after article (5)
5 Type of cattle under an age BSE affected? (8,5)
6 Unfortunately did for two found washed up on a beach? (9)
7 Carry on with former nurse (6)
8 Poet in study, in need of a drink first (6)
10 Sort to leave acting role (9,4)
14 Sold us roe, processed, having no smell(9)
15 Cushy job at home in stable (8)
16 Ringing dope in factory (8)
18 Step one is to climb across cold mass covering the top of Everest? (6)
19 Don’t forget about leaving part (6)
22 Circles vowel in error (5)
