Richard
This were I show just what a really sad person I am.
Leyland fitted a number of different radiators to the Retriever, the bus, that’s the one you refer to (and the type I have got), two variants of the commercial, the one in the picture and the vertical spout with lock.
Then after November 1940 (some sources quote Sep 1941) the small radiator came into use with the angled spout some times called the 'Thorneycroft mod'
Pete
PS sorry don’t get much chance to talk Retrievers, most people just shake their heads and move away quickly in case it’s contagious.