The DH5 didn't serve with many squadrons - 24, 32, 41, 64, 65 and 68 (or 2 Sqn AFC) - so you could try to locate the "war diary" for each of these units at the Public Records Office.
A roster of pilots allocated to 41 Sqn appeared in an Over the Front journal; C E Briant's name is not listed, nor is he shown in the (short) listing of DH5s and their pilots that appeared in Vol No 2.
Good luck
Graeme