You're right Richard, it was indeed Chrysler which took over Rootes between 1964-1967, and in 1978 it ended up in the hands of Peugeot - read
https://www.curbsideclassic.com/auto...-rootes-group/
I quoted George Moore mainly because of the the notion that when Rootes was taken over "all drawings and info was skipped and burnt.” However, according to the Rootes Archive Centre Trust
"a warehouse full of old Rootes documents and drawings" was donated by Peugeot to the ARCC.
I have been trying to find out more info about the 15-cwt RAF Van and there is very little info available. As Bob Allan wrote: "we have very little information about these vehicles and do not know where the records are now". So the search continues...