Across:
   1. Notes in tiny manuscript (6)
   4. Old country song about sailor (6)
   9. 150 to return for Mass (4)
  10. Go over area to find shrew (10)
  11. Feeling of resentment created by rugged characters (6)
  12. Refers to woodsman (8)
  13. Friend takes a choir into local (9)
  15. Rex appears in intelligence document (4)
  16. Seamus O'Hoolihan takes in part of London (4)
  17. Games turn into quarrels! (9)
  21. It may be unhealthy to interrupt endlessly (8)
  22. Country woman has material in abundance (6)
  24. Are 1acs sold here - or their producers? (5 5)
  25. Authentic version of Lear (4)
  26. Quick! Journalist is in river! (6)
  27. Force Mark right inside (6)
Down:
   1. West Side girl carries the French disease (7)
   2. Well-known for not having a bear (5)
   3. Bach met with a tragedy! (7)
   5. Turn to Brighton, maybe (6)
   6. Top people at lakeside restaurant (9)
   7. Very old worker carried nice arrangement (7)
   8. Fire Iris in scam with allowance! (13)
  14. Move white rose, or else! (9)
  16. Shoots King in lips! (7)
  18. A Frenchman holds fashionable ointment (7)
  19. Terrapin quietly left the country (7)
  20. Ragged but sedate (6)
  23. Regular van loads contain grub (5)