That would assume they pre-empted the design application process, surely? If the design was not registered until 1946, they could not have stamped it with anything until approval was received. I suppose that any items made prior would be unmarked.
I doubt if delays would have been more than a year in any event, but could be wrong as it was just post-war and a busy time!
True David, but there's a lot around without the RD no as well, as Christine pointed out. My set isn't RD marked.