_______ _______ _______ _______ DAY by Apex

The unclued perimeter (clockwise from square one) gives four nine-letter words which are missing from the title of the puzzle. The title was recently suggested by 32 in the presence of 11, 22 and 31 (all unclued). Solvers to complete the title of the puzzle.

Across
8 Stars - 19 found in north-east (5)
9 Teaches old English earls to reform (6)
13 Poem turning up in 7 mostly (3)
14 Oil to spoil European limestone (6)
16 Provided very small coin (3)
17 Pilots have left this deserted capital (5)
20 Awfully nice English relative? (5)
25 Almost adjacent (4)
27 Busy Scots need it at sea (6)
29 Employed in house decoration (4)
34 Confusion captured by Old English painter (4)
36 Girl turning in ballet (4)
38 A riddle? Yes in a way' (3)
39 Something old-fashioned round musical instrument (5)
40 Grave solitary man loses heart (6)
Down
1 Very good house call (4)
2 Wickedness in the Village (4)
3 Note network about to wobble (6)
4 Some well-endowed girl (5)
5 Space for parking a horse (3)
6 Wounded uplifted by God (4)
7 Cook again about to perform (4)
10 Weird ending of 'The Lake' (5)
12 Millions in riot destroyed island (5)
15 A fennec badly razed (5)
18 Regrets making sure (4)
19 Nothing against American eggs (3)
21 The old produce some obsolete answers (3)
23 Told story about 'The Demon of Ayr' (4)
24 Note about new Scottish ornament (5)
26 13 about concert-hall (5)
28 One good and necessary dwelling-place (5)
30 Republic helping to build 10 up (4)
33 A moulding clubs may change (4)
35 School party quietly set up (3)
37 Aim mostly to climb mountain (3)