The unclued lights (two individually, both of two words, one an abbreviation, and five pairs) are of a kind. One further theme word appearing every third week should be highlighted.
 

Across

1           Men Prescott battered in dispute (11)
7           Liquid — mostly light red (3)
11         Beat about the ears? (6)
15         One in a suit showing spirit (5)
16         Question and answer about Long Island’s decline (5)
17         Active Liberal in breeding establishment backed the big folk! (6)
18         Local strains from most of Polish region (5)
20         Extremely succulent food for small carnivores (6)
22         Make a meal of a symphony! (7)
27         Colours blended in Dresden (7)
29         Great weight of gold falling off car’s boot (5)
30         Nameless Merseyside ground is far away (6)
32         Old Penny leaves scrounger for basketball player (5)
34         Yellow line round theatre seating (6)
36         Head librarian has spontaneous remark (5, hyphened)
37         Ten reservists — small specks (5)
38         Encyclopédie editor edited 31 books (7)
40         Leonardo’s time (3)
41         Rebirths — cancer’s seen destroyed (11)
 

Down

1           Percussion players adjust public address system that’s not dressed up (10)
2           Mounted soldiers save a line for sedative (8)
3           Opportune moment to proclaim ceremonial with Herb? (9, two words)
4           Distributed hand-outs to the Christian Church many times over (12)
6           What lorry on uneven camber may do a lot (8)
7           Some gain an exemption that’s crazy (5)
9           To obtain acknowledgement, order direct (6)
14         Soundly supported fine old fish disinfectants (12)
19         Outline plan of monthly magazine that’s only partly useful (10)
23         Could be a Birman highbrow (8, hyphened)
24         German car at centre of the Swiss city bearing metal (8)
25         Treat tripe and fish brought up (6)
31         Failed as player, having departed without runs (5)

 
A first prize of £30 for the first correct solution opened on 30 September. There are two runners-up prizes of £20. (UK solvers can choose to receive the latest edition of the Chambers dictionary instead of cash — ring the word ‘dictionary’.) Entries to: Crossword 2425, The Spectator, 22 Old Queen Street, London SW1H 9HP. Please allow six weeks for prize delivery.