Army DEMS mystery

Dear All,
I've found two Glosters who were both killed on the same day, 14/03/1941.
The CWGC states "DEMS personnel".
5187924 Pte Ernest Hale
5187992 Pte William Worby
I've read enough to understand that Royal Artillery personnel, more often than not AA trained, were DEMS, but I'm not understanding why my two Glosters could be DEMS personnel.
I see the two Regimental numbers are very close.
Has anyone got any ideas please?
Thanks,
Ken