Sorted.
As the car was a year old, phoned the Porsche dealership and explained problem, they also refused to give me the owners details, due to data protection, but they did ring her .
Turns out she was going on holiday and took her car round one of our neighbours so she could borrow it. The neighbour said leave it on that drive and I will move it later . The girl went and forgot to leave keys. So Porsche phoned her and she in turn phoned neighbour who went to her house to get spare key.
She must have had a blonde day except she had black hair.
The stupid thing is she didn't even consider puting a note through the door or leave one on the windsceen.
Women never cease to amaze me