Following on from this thread....
I have done some reading on here and found the culprit....
My symptoms were a very sooty exhaust and intermitent smoking under load. No warning signs and no obvious loss of power but I thought I could here the turbo louder than normal as per my thread above.
Sooty rear end...
This would be black after a 20 mile run
Then whilst reving the engine with the cover removed I could see something wrong..... The protective cover on inlet boost pipe was moving. This warranted further poking about and "Hey Presto".... found the bounder
So ..... if your car is blowing smoke under load and seems a bit louder than normal I would start by checking the rubber turbo hoses. Oh and one last thing.... I took the pipe off and wrapped loads of duct tape around it as a temporary repair..... it lasted 5 mins before a hole was blown right through it so don't bother
A happy chappy here now I have found the problem