Reports suggest the fellow has also been seen in the Great Missenden / Great Hampden area, and may be partaking in jogging au naturel (apart from trainers).
As reported below, he could be associated with a black VW Golf, partial registration beginning N604, which may also have the front number plate missing and/or the rear number plate 'accidentally' obscured.
If you have any information, or see the culprit or vehicle, please call Thames Valley Police on 08458 505 505, or dial 999 if you feel you or anyone else may be threatened.