John;
The top picture is of a Car, Light Reconnaissance (British Humber) MkIII
The bottom picture is of a Car, Light Reconnaissance (Canadian Otter) MkI
They were both used by R.C.E. Field Squadrons and Field Companies, although the Otter was designed as a Canadian replacement for the British Humber MkIII, it's performance wasn't has good as the Humber's. The .303 MG you refer to is the .303 Bren LMG that both types of cars were/could be equiped with.
Cheers
