He's come out very well.
There are a couple of points : the Ox & Bucks were an Airlanding , Glider-borne Regiment, so would wear the standard Battledress trousers, not the Parachutists type with the special pockets.
And his webbing would probably be Blancoed one of the several possible shades of green.
I have been trying to find out the usual armament of buglers in action for years, but the Sten seems a likely answer. The other question is whether he acted as a bugler in action ( probably very rare ) or as a Stretcher-Bearer, which was the normal role of musicians.