Sorry for the delay in replying. I am very pleased to confirm that the problem appears to have been resolved.

As the car was due for a 60,000 mile major service, I booked it in with a VW dealer, with a request to check the "pulling back" fault. When they returned the car to me, I was told that the firm had not had time to check the fault and it would have to be taken back to them at a later date, which I thought was very inefficient of them (especially as they are 1 hours drive from my home). What they did not notice was the fact that, after the service the problem had dissapeared.

I guess I may have saved a considerable amount of money, had the "fault" been turbo related, although I am surprised that the firm did not take the trouble to do a quick check/diagnostic prior to the service. But there again, they are are VW dealers!