Thank you guys, you certainly know your planes.
This cj, I've taken over from Judy (with her permission). It's my Dad 2nd from the left of photo, and I'm pretty sure he trained on Wellingtons, so that fits. All 3 photos were probably taken around the same time in North Africa. They are the only pics of aircraft among hundreds of photos taken all over Egypt, Palestine, Syria & Lebanon.
I've had another look at the original & blown it up. Can't see any stringers.
Michael, your explanation about firing order of 9 cylinder radials is excellent, I knew they were mostly an odd no of cylinder for balance, but didn't know how they worked.
Malky, I didn't know there were a few even no. radials in service.
Thanks again, most grateful.