Took the car in today and found the problem - front drivers side wheel is bent
Looks like the mammoth potholes in Hungary are to blame, and for the cost of a new alloy.
The chap spun both front wheels up on the machines in front of me and you can see the deformed on is slightly off round.
Seeing as it's only noticeable over 100mph ill leave it for now, unless it gets worse, or makes my 200mph runway days too nervous!!!
Thanks for your recommendations!