Pat, Do you mean C.7372 ? 7373 was an AJS contract.
Which MoS records have you been looking at ? This contract was of course placed at the point where the BEF needs were great and many bikes were taken from factory stocks or built up from available parts.
The Ordnance records suggest that a total of 215 machines were supplied, made up as follows :-
150 x 500cc
65 x 350cc
87 x 500cc VH
38 x 350cc NH
63 x 500cc VG
27 x 350cc NG
I can find no reference to a 'W' prefix so these should have been normal civilian spec machines, perhaps with simply (but not necessarily) a colour change. In fact, Orchard & Madden state that the Ariel factory records show supply of both single and twin-port head versions.
Only a check of the engine and frame numbers of the bike in question will shed further light on whether this particular bike was a VH. Bearing in mind subsequent rebuild procedures, it is not without precedent that a VH engine was placed in a W/NG rolling chassis and then reissued with a new census number. I don't believe that any breakdowns of these rebuild numbers survive.