Completely out of the blue today I was discovered by the new owner of the car I spotted in this original post!
Whilst I was attending a Cars n Coffee event in Liverpool in my Europa a guy approached me to say that he too had a Banks Europa - the very car I saw last year, it was J (71) reg, silver mini lite type wheels, Banks racing yellow (think yellow fluorescent marker!) with a Banks 47 body (my eyesight isn't too bad with a closing speed of about 140mph eh?!!).
Even more amazing is that it is relatively local to me now(15 mins away), the previous owner lived close to where I spotted him on the M5...it's a small world!!!
I have directed him towards this forum.