He’s definitely from a fusilier regiment, the 2-piece title typical of fusiliers is apparent on his shoulder strap, although by the end of WW1 over half of the fusilier regiment’s had adopted one piece titles. Both RA and RE had modified their collar badge designs with ‘UBIQUE’ honour scrolls beneath in the early 1920s, and their shoulder titles did not include a grenade. In general collar badges were ordered for universal wear across the Army on khaki service dress between 1922-24. If we can determine which fusilier regiment was in Dover post WW1 it will be possible to make an ID.
Postscript: I can confirm it was the 1st Battalion of the Lancashire Fusiliers, who were based in Dover in 1925. This fits with the 2-piece shoulder titles, as along with the Royal Welsh Fusiliers, they were the only two fusilier regiments to not adopt 1-piece titles (although the LF did later on).
NB. Do not rule out that he might previously have served with the Royal Dublin Fusiliers, as when the South Irish infantry regiments were disbanded in 1922 those men who wished to continue serving transferred to other regiments.
