Across:
   1. Putting off top Conservative leader’s return to island state (15)
   9. Closed down pit without a test!... (7)
  10. ...Pastimes organized without a 20 (7)
  11. Final farewell transmission starts before journey (4)
  12. Join never-ending iTunes mash-up (5)
  13. Predator is back in the morning at University (4)
  16. Speaking of a Conservative alternative (7)
  17. Jolson is involved in disturbance with unequal sides (7)
  18. Irritated when horse in river died (7)
  21. Car, a Beetle, entered in road race (7)
  23. Sat with Belladonna in The Shire (4)
  24. Firm leader takes a drink (5)
  25. The French sailor is first to be skilled (4)
  28. I stop a male changing artistic technique (7)
  29. Imagine having no current at all to produce dynamo (7)
  30. Decrepit red nag gets skin bug by river. Could be a feature of outdoor life (6 9)
Down:
   1. Stupidly fight only ten on pierhead? That’s enough for Porgy! (6 2 7)
   2. No car in an illegal race carries a sound instrument (7)
   3. Lead and rule without force (4)
   4. Caresses back joint when speaking of part of London (7)
   5. Prisoners break out! Aim nets! (7)
   6. Daughter leaves broken spade in part of church (4)
   7. One turned out for trespass! (7)
   8. Sounds like some fish aren’t happy here – but we are! (2 5 4 4)
  14. Happy students find happiness all around! (5)
  15. Restless slaughter of lark! (5)
  19. Handler, maybe, carries in swimmer (7)
  20. Deliver 21 down... (4 3)
  21. ...Loaf made from flower? (7)
  22. Thanks young man left in display (7)
  26. Is Leicester partly land surrounded by water? (4)
  27. I lug out fruit (4)