2688: 4 ÷ 4 = 8

The unclued four-letter solutions can be paired in a particular way to form the four remaining eight-letter unclued lights.

Across

1 Burns searches thoroughly around Union Street (8)

5 Developed green, variable power (6)

10    Labour man’s entertaining turn (5,5)

12    Irish backing chorister on Venetian bridge (6)

13    New tune outside? (5,3)

16    Account of help sent back to railway (5)

17    US cocktail that’s pungent (7)

18    Sporting cry in match – touch and go, finally (5-2)

20    Sunday crossword for Tom, Dick and Harry (8)

25    Stiff paper, way-out neckwear? (3)

26    Game of bridge (7)

28    Movie buff reviewed Cain set (7)

29    Lengthen in both directions (3)

31    Spa experience for others with French priest (4,4)

34    Attention to story run in the past (7)

36    Locates refined sugar (7)

39    Stealthy advance of cortege regularly quiet (5)

41    Long and limp Scottish seaweed (6)

42    Measuring device at spa with parking machine (10)

43    Harley Street doctor – no sharer of tea (6)

Down

1 Tenor dear to the Italians around the States (6)

3 Floor and yard below shop (6)

4 Traps wriggling fish (5)

7 Ripe apples are done in (5,2,4)

9 Huns leaving White Russian bewildered plant (8)

11    Wandering errand-boy loses little brother in area of Belfast (7)

14    Verve of Patel annihilated (4)

16    God-given authority troubled Irving and Edith (6,5)

22    Gibbons does a send up (4)

24    Roller coaster sounds best aboard ship (7)

25    The heart of holy Adriatic port (4)

27    Bishop left crazy debutante and took up the slack (8)

30    Insinuation that Sri Lanka upset Richards, for starters (4)

32    French confectionery items may be tastier without one (6)

33    Five hundred trees, perhaps? Not here, surely? (6)

35    It turns round and round round! (5)

Download a printable version here.

A first prize of a £30 John Lewis voucher and two runners-up prizes of £20 vouchers for the first correct solutions opened on  17 February. Please scan or photograph entries and email them (including the crossword number in the subject field) to crosswords@spectator.co.uk,