If it is Glowworn then it must be pre 1940.
https://en.wikipedia.org/wiki/HMS_Glowworm_(H92)
Possibly Gibraltar 1938-39? In 1939 the Infantry on the Rock were 1st Bn. Welsh Guards, 2nd. The King’s Regiment (Liverpool) and the 2nd Bn. The Somerset Light Infantry (Prince Albert’s). I do not think he is Welsh Guards as the collar badge is not their leek.
Prior to that the 2nd Bn. The Royal Norfolk Regiment and the
1st Bn. The King’s Own Yorkshire Light Infantry were there in 1937.
Or may be Malta? The Glowworm had moved to the Maltese end of the Med in 1938-9 and was doing escort duties there. In 1939 Malta's garrison was a single infantry brigade; comprising the 2nd Battalion the Devonshire Regiment, 2nd Battalion the Queen's Own Royal West Kent Regiment, 1st Battalion the Dorsetshire Regiment and the 2nd Battalion the Royal Irish Fusiliers.