Ah well no takers!! so after removing the undertray I found that the big plastic hose has a mounting bracket bolted to the engine and I also disconnected the dipstick bracket to gain better access. I still used a bar to lever a little more room and managed to get the bolt out of the rose jointed fuel feed pipe.
Turns out the bolt is actually a Non Return Valve. Explains how the pump maintains feed from the fuel tank.
Replaced the copper seals and used a magnet to help align and screw the valve back into place.
Not an easy job so I hope this helps someone else out.