Phillip,
A bit off topic for me as a weasel man
but I do know that Bigtyre in Toowoomba QLD;
http://www.bigtyre.com.au/index2.html
has a mold for Bren Gun Carrier wheels. I think it may be for Australian wheels though???? Could that tyre mold be altered for English carrier wheels?. The rerubbered tyres do look very impressive.
Cheers
John W.