Good news- hopefully!
So hopefully all is fixed!
Swallow's recommended Alex has had the car for a week. He found four problems I think, although I haven't been back to collect yet he sent me a detailed email with pictures. Firstly it seems the latest radiator (#14) fitted had inappropriate screws, these had punctured the front of the rad. I have a nice picture of the water feature that ensued when he pressurised the rad(this one hadn't failed noticeably when I brought the car in). Secondly the previous rad(#13) which I brought from the original garage had failed where some rivets joined the matrix, different brand of rad but seems like a manufacture issue. Thirdly the heater matrix was partially blocked, and finally the fan was mounted without rubber vibration dampers.
The screws issue doesn't need explaining, but I wonder if the final two issues could have caused the poor quality (Chinese) rad #13 to fail. I wish I had all the others to look at. Previous work had all assumed that the engine was at fault- maybe it was but it seems like the poor rads were the issue too.
I'll await getting the car back before I talk to the other garage- but I they must owe me something here. At the very least the final rad they fitted was punctured by the screws they used to mount it. I paid for this work.
Additionally, I never had any trouble with the rad until they changed the original rad when my new engine was fitted two years ago. It wasn't leaking at the time either but they pointed out it was the original from new rad and being 11 years and 100000 miles old probably needed changing while the engine was out. What a mistake that was...
Thanks to all of you and Swallow in particular for his recommendation- especially if you're now donating parts as well! 👍👍