...........just found some more links to MONAB's in Australia, with some photos showing vehicles, a quite a few British ones, marked with RN serials, inc. Bedford QL tankers and GS cargo types, Fordson WOT6 GS cargo, Austin K6 radar scanner, Fordson WOT2 GS. If you go to the following link, which shows a selection of photos, click on "Nowra image 17", this shows a row of Fordson WOT6 GS trucks and a jeep all with RN serials.
http://www.royalnavyresearcharchive....S/M1_Album.htm
It is quite possible that vehicles needed to be supplemented for a number of reasons and were obtained by "local" resources.