Across:
   1. Difficulty is with leaders of society usurping everything (5)
   4. Crown's difficulties include large one: unpopular grain tariffs (4 4)
   9. Political leader from east Vietnam set at securing some (9)
  10. Army perhaps in favour of church? (5)
  11. see 13 down
  12,22. It may shows degrees of response to 19th century injustice ... cosy 5 of non-conformists gathering in 13 (6 6)
  14. Meth criminal sometimes said to be pitted against us? (4)
  15. Favours commercial vehicle with awkward stage (10)
  18. Decide sins can be rehabilitated in expression of contrary view (10)
  19. Pursue bit of nirvana in humble dwelling (4)
  22. see 12
  24. Odd ones go for spree, their alcohol making for scene of 17 in 13, 16 / 8 / 1819 (8)
  26. Grey like chick's grandmother (5)
  27. In out in out... it is an instinctive thing (9)
  28. Witness of 13 11's forerunner (8)
  29. Proverbially good 28 came close with a broken leg (5)
Down:
   1. Understanding that thing is broken (7)
   2. Tars and feathers arse, outing the renegade (9)
   3. Workers accepted: editor does, ultimately! (6)
   4. Requisition Officer and Buck perhaps embrace, man-to-man (10)
   5. Round square? (4)
   6. Socialists let fists fly (8)
   7. After argument turned over, holy man seems least impressive  (5)
   8. Ones wanting new liberties, with removal of the leader? (6)
  13,11ac. Originally run masthead... nice rag whose first 1 across was in 1821 (10 8)
  16. Tough grunge arrangement featuring sick turnaround (9)
  17. Nasty behaviour ruined nice love (8)
  18. Revolutionary fiend has country houses around 25 (6)
  20. Beat relentlessly when no truce arranged (7)
  21. Ugly grime, primarily effluent, in system (6)
  23. A herb liberally used for treatment of drug addicts (5)
  25. "Caesar-style" shift of four gear City (4)