It's a 2 pounder portee on a long wheelbase cab 12. The pic above is a Ford version; the one in your image looks to be a Chev as served in the Western Desert campaign.
It runs on 10.50 20 tyres, and is a 158" wheelbase.
This particular one is a replica, based on a Ford F60L cab 12 by John Belfield.
More pics of it
here.