The disc at the front has the information:
Valve Eng Coy
My grandfather is second row from the back and four in from the left. I have no other names.
The second photograph has a complete set of names (my grandfather is in the front row , third from the right).
Starting from the back row:
Jean Stewart, Beth Downie, Mina Campbell, Sidney Smart, Ray Ballantyne, Robert Smiillie, May McAsh, Tom Menzies, Mary Jackson.
Willie Greg, Grace McKechan, Edward Cumming, Lil Jardine, James Robertson, Jean Kelly, W. Smith, B. Henderson, R. McQueen, Enid Pearce.
J. Campbell, M. Campbell, E. Moffat, R. Flinn, M. Blair, J. Anderson, M. Tait, J. Pettigrew, J. Dunlop, D. MacKay
J. Hogarth, N. McAllister, A. Miller, J. Black, J. Moir, G. Shotbolt, B. Menzies, W. McMaster, I. Fullarton, W. Gaw.