I have just taken a print down the road to Dave and Rory Ballard, they are far better at this stuff than I.

The sign that we can see, if it is red top half and blue bottom, is the 15th (IOM) Light AA Rgt and it seems something like the 73 is repeated again on the gun axle. It was customary to have the the sign is combined with the "usual" desert rat as Dave's truck has. It may be the rat is depicted separately on that lower right sign or this may perhaps be the 20 mph speed plate. From another thread, this alludes to convoy speeds, with the crew on the gun I doubt if you'd want or be allowed to exceed 10 mph.

There is another insignia in the centre panel which we cannot clearly see but believe this to be battery number sign.

The truck is a CMP but difficult to tell if its a 12 or 13 cab, the side light is prominent and the mirror somewhat higher than expected; it is a GS not a LAAT owing to the metal tail-gate whereas the LAA tractors have a canvas arrangement and a proper seat placed centrally facing rearwards for the gun brakeman; this duty being performed here by the soldier in the middle probably crouching or kneeling, perhaps even on a makeshift seat like an ammo box.

The Crusader on the left is interesting, the white cross denotes it is acting as an enemy tank and parked as it is, probably KO'd for the exercise.

R.