Richard, indeed a good day was had by all.
I find it interesting to see CMP trucks being used like this which is quite rare here. Also to compare this 6x6 with its big wheels with the ubiquitous GMC CCKW with smaller wheels.
Seeing the side marker lights, this could be an ex-Danish Army C60X.
The Danish had a number of GS versions with a high sided cargo bed per the attached pic.
But this preserved example seems to be fitted with an ex-GMC cargo bed.
