Hi all, Sorry for the delay in posting an update.

I am marking this as fixed, after various tests and cold starts etc I found the pipes from the filter on the wrong unions.
Very bizarre as this has done in excess of 15000 miles set up like this - no one but me has worked on the car and I have never removed the pipes before!

Another one put to bed!

Thanks for the input, all greatly appreciated.

Liam.