'Q' plates usually indicate an ex-military truck. If such a vehicle has a normal registration as in the photograph it was probably issued from new and it never was a military vehicle.
They have some similarities but also many differences. The serving hatch is completely different and the Matchbox van is far narrower. The Matchbox trailer has a great deal of internal detail even down to kitchen utensils hanging on the wall! They can be found at swapmeets very cheaply and do well from a repaint and addition of details such as figures.
None are known to have survived, but who knows what may be lurking in a barn somewhere? The chassis used was actually intended for a bus/coach and it often happened that the horsebox body was removed and replaced by a bus body. Many such chassis were also exported (minus their bodies).
For those who may be interested Base Toys are producing a third version of their British Rail FG crewbus. This one with a smaller crew compartment, only one window behind the cab.
I read the registration as LSD 387 which was issued in Ayrshire March-May 1958. All other L?D numbers were issued in 1950 or before, too early for that style of bonnet. I'm sure I've seen a photograph of that particular ferry, Firth of Forth perhaps?
If you want a TV camera and crew shooting a scene take a look at the offerings from Subbuteo. These are 1/76 scale to go with their tabletop soccer/rugby/cricket games. They also made spectator figures, most with long scarfs but these were seated figures. If you are a Morcambe and Wise fan they even made two old men sitting in deck chairs! (Cricket spectators). Subbuteo is now only limited production but can be found on e-bay.
Another source of models and figures suitable for 1/76 scale is Micromodels, their motorcycles in particular. They produced many models tied to TV characters including Dr. Who but these are sought after by collectors and may be expensive. As well as the above they made an Isetta bubble car that is a very accurate representation and is closer to 1/76 than the Cararama one and they also made a couple of frogmen with articulated limbs. You can find them on e-bay but they don't come up very often.
I have just purchased a 'OO' scale diecast model van from Hong Kong via e-bay. No complaints about the dealer or price and the postage was free. The diecast had the appearance of an Austin A40 van of the early 50's which is why I decided to purchase. It arrived this morning and despite being a solid one piece casting was quite well detailed, the problem is that the bonnet casting is from an A30! not an A40. There is the possibility that this vehicle is an Australian model but it does look strange.
L to R 1) AEC mid 30's to 50's, 2) Albion, these were often old fashioned in appearance and could be up to mid 60's 3) AEC Mk. V, late 50's to late 60's 4) Bedford TK, introduced mid 60's, I last saw one in use as late as 2005!