The vehicle could possibly belong to the 3rd Infantry Anti-Tank Company of the 3rd Infantry Brigade, C.A.S.F. (1st Division, C.A.S.F.), with the photo having been taken sometime between 29 May and 6 June 1940 when the 1st Division, C.A.S.F. (with Canadian ancillary units) was formed into a self-contained body known as 'Canada Force' and were in the Northampton area as part of G.H.Q. Reserve (directly under command of G.H.Q. Home Forces) to reinforce the troops on the east coast between the north bank of the Thames and the south bank of the Humber in the event that the Germans would attempt to land in the British Isles following their successful break into the Low Countries on the continent.
At the time of the deployment of 'Canada Force' to their assembly area in the Northampton and surrounding district, the Arm of Service marking of the 3rd Infantry Anti-Tank Company (3rd Infantry Brigade/1st Division, C.A.S.F.) would have been the figures '35' in white on a brown background (brown being the background colour of the Arm of Service markings for the junior infantry brigade of an infantry division and the Arm of Service marking serial of '35' being that which was assigned to the 'Infantry Anti-Tank Company' of the junior infantry brigade of the division, at that time).
The vehicle is an early 1940s Cab 11 15cwt with the 2A1 box, probably a 2-wheel drive.