All names numbered from the left. Where I can remember them, I’ve put first names in.
Rear row. 1. Bill Spilsbury. 2. R Mabbut. 3. Me, Alan Courtman, 4. M W Reynolds, 5. R J Howard, 6. I Cowell. 7. Michael Hibbeard, 8. A. Campbell,
9. FA Rabbetts (Bunny?), 10. Anthony Oulds (Tony or Titch).
Centre row. 1. G G Andrews, 2. R E Williamson, 3. J T M Wilson, 4. R I V Smith, 5. R Davies, 6. J. Feller, 7. W R Birnby, 8. R Austin,
9. A Joiner, 10. Dave Head, 11. M G Brown. 12. J Graham
Front row. 1. N Bramley. 2. D J Austin, 3. D E Wooley, 4. M Baldwyn, 5. B J Creasey, 6. E Littler, 7. H Crouch. 8 Yeo Elliot, 8. PO Tel Wallace.
9. A Jackson, 10 R J Lee, 11. D Rushton, 12. J J O’neill, 13. M Hutchins.

As both the Instructors from 45 mess are in the photo I think we can assume that this is both 312 & 321 classes.