To be honest, for a while, I was thinking they might not have had one! :-\
I'd seen Roger Manton's model of "Western Advocate" on the JLTRT stand and he'd made a driver's jacket out of Milliput or similar and hung it on the back of the door, so I thought "good idea, I'll have some of that", but rather than a jacket, I just installed hooks. Of course, once I had fitted said hooks, I couldn't find any inside cab shots that proved things one way or the other. :-[
You having asking the question, has made me dig out a convenient Western book ("Diesels In Depth, Westerns", by David Clarke & John Jennison). It took me a little while, but at the top of page 39, I found a picture of D1005 "Western Venturer", with what appears to be a coat or jacket hanging on the back of the door, so we know at least one Western had a hook on one of its cab doors, though whether my hook is the right size or shape is unknown. I think I see why Roger stuck a jacket there. Now, where's my Milliput gone....!
Regards
Dan