Thought i would give an update and say thank you for all the responses!

Finally (3RD time lucky) the sump seems to be leak free ****Trying not to temp fate ****

I used a combination of suggestions from above so should say thanks to every one.

Here's what i did for in case anyone stumbles across this thread and has already tried every thing.

1) Strip and remove ALL old sealant especially from and around the half moons
2) Clean mating surfaces using degreaser and acetone.
3) Use spray mount to attach the nice new payen gasket to the engine block
4) Use appropriate studding in four corners to align the sump (and stop the gasket from being knocked out of line)
5) Install the sump and tighten all bolts using a screw driver, starting in the centre and working outwards.
6) Run your fingers round the outside of the sump and make sure the gasket hasn't been pushed out anywhere.
7) Go round the sump and torque up all bolts (to 5NM) after thread locking all bolts. (I use loctite 243, medium strength, vibration resistant etc)
8) repeat step 7 ONCE.
9) Pray, and drive


Rob,