Trying to identify this truck

[Alex van de Wetering]

I have got two questions concerning the bridging truck in this picture.

1 Can anyone identify the bridging truck in this "famous" picture?
AEC Marshall? Albion? Guy?? Has anyone got any ideas?

2 Does anyone know if there are any of these WW2 "bridging-trucks" surviving in the world? Maybe a restored example?
I am thinking of building a scale model of a bridging truck in the future, but I still have to decide what model.....Guy, Albion, Diamond T? I am looking for detailed info on the bodies of these trucks, so I am trying to locate any surviving examples.

Alex van de Wetering