Across:
   1,8dn,12ac. 'It' marks anniversary of 24 13 in Japan essentially by ad: "No 'it'! Never preside over swamping of a street!" (8 10 3)
   5. Compact computer line suitable with small operation (6)
  10. Pan clique concealing murder (7)
  11. Barge in as one turned out (7)
  12. see 1 across
  13. see 24
  16. This lay about haphazardly (7)
  18. Liar set out to become one honest about prospects (7)
  19. He boxed at Rome Olympics, among medalists (3)
  20. Rout badly using awe & shock, or defeat by attrition? (7)
  22. Poet X writer Elizabeth with elegiac Eve, doubled heart! (7)
  24,13. 1 across as major German philosopher, with old English cunning, headquarters with King in U.A.E. (5 5 10)
  26,1dn. Alternate parts in throaty duets OK as a way to get two people to work (3 4)
  29. Public messages groom rampant 30 of group, such as Koreans after 24 13? (7)
  30. Huge income raked in by monarch is sick (7)
  31. Modified Maoist philosophy (6)
  32. City hit by 24 13 violently shook, as may take seconds (8)
Down:
   1. see 26 across
   2. Forms I pass around, to take in both sides (7)
   3. Only love's dashed, victory denied (4)
   4. Minor player in complex trade (5)
   6. Quaint, date passed? (10)
   7. One result of 24 13, a must in 1 across (7)
   8. see 1 across
   9. She was said to be "not amused", and indeed some soldiers got her cross (8)
  14. From a bit of math (rough)... putatively, how much you get done (10)
  15. Forest's rim damaged in results of 24 13 (10)
  17. Spar ends... marry sad lunatic! (8)
  21. Wobble of note in molto agitato? (7)
  23. I tore up California's disgusting material (7)
  25. City hit by 24 13 also featured kindly extremes (5)
  27. Also time to replace second singer (4)
  28. Site of significant fort in Bagram (4)