Cryptic crossword No 2,639

Across

1. Old kings' homes encoded in PM's diary (8)
2. A general overseas (6)
3. Notes, perhaps, a Greek character takes as written (5)
4. South Kentucky is where to look for stars (3)
5. Paper issue to be returned to school head (5)
6. Worker in secure city (5,2)
7. Brief sunny weather reported (7)
8. Wander in Italy, we hear (4)
9. Ohtani one to get away with being jammed inside in UK! (6)
10. Broadcast melody (3)
11. 12 in America briefly in tiny trip (1,1,1)
12. Twitch has untrustworthy paper contained - disastrous! (6)
13. Macabre writer to start manuscript in Limerick, perhaps (4)
14. Unusual present for snake (7)
15. Sweet prepares her best (7)
16. Glasgow's ultimate wanted for authors' ceremonies (5)
17. Graduate with new fellow (3)
18. It can be hard to tell what it ruthlessly conceals (5)
19. A drug's distributed to wards (6)
20. Pie crust in pieces in cinema (8)

Down

1. Sexy beast regularly collecting looks (4)
2. Not right; amoral corruption in second mission (5)
3. Heartless father with advanced article in post (5)
4. Shifting as sliding notes? (9)
5. Return legs are about the same (9)
6. Under pressure for pound cakes to rise (8)
7. Whisk lover away? (4,2)
8. Shoot for several seconds before grip is loosened (5)
9. Domesticated beast chews meat (4)
10. Bishop breaks rule, making chaplain sadder (5)
11. Simon ate cooked dinner (3)
12. Mass uprising leads to Ecuadorian prison breakout, but it works out? (5,4)
13. Siren breaks up family (5)
14. Largely like many Spanish songs (4,2)
15. Shakespearean heroine named Erica does perform (9)
16. Cuban, perhaps, after brewery lunch gives what might be impression of a dog! (4,4)
17. Orwell's farmhouse reveals return of some measure of resistance (3)
18. Springfield, Oregon perhaps in need of cleaning (5)