Across:
   7,2dn. What Britain dropped on D-Day hit German force hard; suffering, in German capital stock index hence dropped hard! (6 9 3 5)
   9. see 16
  10. Old broken leaders of last army regiment forming unit of 26 (6)
  11. Art of poseur in a lavatory piece? (6)
  12. A drug for Victoria perhaps (8)
  14. These vent your insides in old age (7)
  16,9. Granny, initially confused, got hint: tip teen offered capturing 18 (7 3 5)
  19. Clothing institution for the modern girl (8)
  21. Eventually allies let Russia dream up rules which could be applied to the letter (6)
  23. Former leader advising "grab bottom right in the middle!" (6)
  25. Nice herd developed, given more nutrients (8)
  26. D-Day advance initially caused uncertainty in foreign army encircled (7 8)
Down:
   1. Problem boy, different (6)
   2. see 7 across
   3. One who made waves and stirred local riots (10)
   4. Shadow hit lampshade from 6pm (7)
   5. Suggested unit for 26: Royal Crusher (6)
   6. Farming city ordered rain (8)
   8. Lads suffered without first rate drug (3)
  13. Dubious arrest, detaining certain government officials (10)
  15. In conclusion, suggested unit for 26 given extra respect (8)
  17. Death at Chernobyl from 4pm (8)
  18. Dead Sea Scroll author capturing start of Christian spirit (7)
  20. Falconry isn't regularly suggested as unit of 26 (6)
  22. Quietly get through to deliver message (6)
  24. Team missing ultimate drug (3)