Well I have tried everything,

Battery charged
Checked and cleaned plugs on rear diff
Checked fuses F2 & F42
Cannot be the module in the dash as DRC and Hill decent buttons are working fine.

Any one have any new ideas??

Many thanks Clive

Ok the latest update and thread completion...

In frustration called Austen at Bell Engineering who was extremely helpful.

Drove from Belgium to their garage close to Birmingham and now the car is working fine. The benefit of the visit is that Austen has all the parts that you could possibly need and can almost guarantee success ( as long as the problem is with drive train ).

Nice people, friendly, helpful and explains everything wonderfully. I understand a lot more how the system works and seeing the inside of the Haldex gives you confidence if you have to do it yourself next time.

I would recommend them to all... If it ain't ***ked don't fix it