[Alex van de Wetering]

hmm, good one.

For a moment I was thinking that it might be a partly dismantled Valentine Bridgelayer...the "barrel" not being a barrel, but part of the bridgelaying equipment. But, I have to say that Adrians point about the Archer engine covers are rather convincing. So, I would also say an Archer with some other gun fitted...maybe even 25pdr? It's post-war Dutch, so Bridgelayer, Archer and Valentine used as OP could be found in one of the vehicle dumps. Mismatches and strange combo's used for training purposes in Dutch service were no exception in the immediate post-war period.

Alex