The unclued lights (one of two words) and four others clued without their thematic definition are of a kind.

Across

1    Two little boys tapped their heads (6)
7    Birettas seldom reveal this tuft (6)
13    US challenge to foil and dismiss at the wicket (5)
14    Material from The Spectator, London (5)
17    Salary and gratuity, collected by mail (7)
18    Incandescent, he’d be forced to put rubbish out (3,3)
19    Infection covered by the oculist? Yes! (4)
22    C19th biologist’s not left film director (6)
25    Violinist’s bow? No, the other end! (5)
26    Followed the progress, we hear, of Lenten psalm (5)
33    Study Latin on express (4)
36    Live broadcast with the French (6)
40    Friendly greeting unwanted amongst Heinz’s offering? (3,4)
41    Spirit lamps Greek characters bore round end of Parthenon (5)
42    Gents harbouring black timber wolves (5)
43    Hatchetman? (4-6)
44    In some ways tiny – but kids love them (6)
45    Cost I’m checking for Not Going Out, say (6)

Down

1    Written permits for roads over the mountains (6)
2    Read intensively of young Thomas in fairy tale (5)
4    Ballerina who pulls the sleigh (6)
5    Wood nymph’s uninspiring notice (5)
7    Nursery rhyme character’s pussies (3-3)
9    Where some, oddly, imbibe alcohol in Massachusetts? (5)
10    Sandy 26s by lake and range (6)
16    Fuel ruined a chair and tent (10)
20    Clay theme word with top missing (4)
21    Guard bird consuming bit of fat (9)
23    Four points for slave (4)
27    Ten acer varieties with leaves having notched edges (7)
29    Eleven in Germany by spring with prehistoric arrow-head (3-4)
30    Elaborate repast comes to a fine end (6)
31    These marks are the first bit of direction in mosaics (6)
32    Walks the dales topless in France (6)
34    Romans’ new demand (6)
35    Last of the unknowns, an All Black egghead (5)
37    Lout in outskirts of Leeds lounges around (5)

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A first prize of £30 and two runners-up prizes of £20 for the first correct solutions opened on  23 October. Please scan or photograph entries and email them (including the crossword number in the subject field) to crosswords@spectator.co.uk, or post to: Crossword 2625, The Spectator, 22 Old Queen Street, London SW1H 9HP. Please allow six weeks for prize delivery. The dictionary prize is not available at present.