Thanks for further comments.
There is no smell when the engine is running whether stationary or on the road. There is never a smell in the engine compartment. When the car doors have been closed for a couple of hours, whether the car has been previously running or not, the smell will have returned. On Sunday we kept the doors open for 5 hours. It was not run at all. I went out to it this morning, opened the door - there was the smell! Distinctly of a petrol nature. I'm hoping to get it to the VW dealer on Wednesday.