Edward,
The open topped version of the Rolls Royce armoured car used by 11th Hussars had a Boyes ATR firing over the frontal arc only and a pintle mounted Bren. These were mixed with the turret mounted MMG versions.
The Armoured cars operated by the RAF were all converted to ATR and MMG in a turret with a Vickers K (2 Armoured Car Company) or Bren (1 Armoured Car Company). Note that these were not RAF Regt Armoured Car Squadrons as the the two Companies did not join the RAF Regt until 1946.
Both operated with Morris tenders, had limited infantry support (dismounts aboard the tenders) and 'machine gun cars'. The exact nature of these is not disputed but appears to be open backed Rolls Royce armoured cars with two or three MMGs - having ripped the turret off, a bit like a Kangeroo.
Wikipedia has pictues of both the Army version (your link above) and the RAF version (
http://en.wikipedia.org/wiki/File:Fordson_Armou... ) - the name Fordson was added when elements of the chasis and running gear were modified with Fordson truck parts.
During the same period No 2 Armoured Car Company also operated a Flight of captured German tanks in support of the RTR in North Africa. Now that could give you quite an interesting force - Pz 3s, Pz 4s, Rolls-Royce (with save and ATR), Rolls-Royce with extra MG and some trucks with infantry....