Across:
   2. Mother of crowd ambushes (3)
   7. Bad ending is PM's bleak outlook (6)
   9,27. 17 exertion of 4 - a Mr Nincompoop on small patch of ground bearing its weaponry (8 8)
  10. Dance music on trail with soldier seems at odds (10)
  11. "The King and I" involves love for oriental creatures (3)
  12. Art is fresh way to get high (5)
  14. Master, it's abuse to do this! (8)
  15. Succeeds in throwing most of the elderly into streams (7)
  17. The most lowly can be miraculously cured by holy man (7)
  20,2dn. He did empire's dirty work, and worked darn greedily (8 4)
  22. John, a crazy guy in the bible (5)
  24. 29's mass elimination out of vainglory (3)
  25. Suppression of most of the nonsense, with mischievous glint (10)
  27. see 9 ac
  28. see 8 dn
  29. Father of destructive acts: disillusionment's beginnings (3)
Down:
   1. Perhaps prison hit-list includes many independence leaders (6)
   2. see 20ac
   3. Mothers receive top decoration from national hero (7)
   4. Inverting cup on broken rib... this occupation! (7 3)
   5. Carbon-free rockets damaged by someone putting coal in (6)
   6. Rascal, I'd run off and join the revolutionaries (8)
   8,28ac. Punjab boss with bizarre claim: he had nothing but worthy leader in 2 down? (7 1'5)
  13. No good to growl at diplomacy, this was about oppression (7 3)
  16. Pray love can be restored after excessive conduct (8)
  18. This was much of 10th century England (and Wales mostly different) (7)
  19. Decorated and admired around nation's beginning (7)
  21. Put upon to take time with right imitation (6)
  23. Curiously, the run chase is his specialty (6)
  26. Stepped up party's right (4)