Solo. I went along a minor road and then paid £2 to go on paved tracks through forest (Aston Hill) to where there is a café. There were signs to the highest point of the Chilterns and a 0.75 mile hill top path. I thought the summit was at the end of the 0.75 mile path and walked the almost level path/track (with one or two investigations of the possible highest point off the track) until I reached a road, which is where cars exit the forest. Walked back to the car, realised my mistake and went to the supposed summit of Haddington Hill which was only about 100m away! There are stones and a plaque at the summit. It is difficult to say that this is the highest point as it is an almost level summit ridge.