I live close to the area and have seen a paramotor on a few occasions swanning around, normally west of Brill on the road to Bicester. 1st time was at approx. 2 feet off the ground having to add power to hop over hedges. Later sightings were at about 300'. If was him/her, they're certainly getting braver with the height.
in the region of about 200m as he/she was descending through my level.
- does make me question if it was a paramotor though.