My van has the cement sheeting on the sides, underneath are cut outs - possibly window holes. Photos of a van with registration DT4114 appear to exist. There has been speculation that this van is actually my van (thanks to Harvey Pitcher for the photo)-
The image of the van during restoration looks very much like my van. The top photo is interesting - you can see through all three side windows. This would not be possible on most vans because of the internal door shroud. I put my hand inside my door shroud and found, yes, a covered hole.
Perhaps the front grill panel and side door shrouds were sourced from an earlier J type, not a JB type? This could explain the front grill badge being from an earlier vehicle.
I quite like the top image - I wonder how hard it would be to go back to 3 windows...