There a two possibles but I think this is the best choice:

Francis Richard Lines, Service Number 21073

F/O w.e.f. 06 April 1926
F/L w.e.f. 01 June 1932
S/L w.e.f. 01 April 1938
W/C w.e.f. 11 March 1940

His branch is given as Equipment and he was qualified in explosives.

Regards
Ross