Inspired by his experiences during the "liberation" of the Isle of Wight Festival 1970, in which the fences between the paid event and free gathering outside were torn down, Dwyer developed the idea of a truly "free" festival. An acid trip in Windsor Great Park led to the notion of squatting on the former common land that had been in Crown ownership since being reserved for royal hunting by William the Conqueror, and he began to organise what was to become the People's Free Festival. Windsor Free Festival was the forerunner of, and inspiration for, the Free Festival Movement, particularly the Stonehenge Free Festival and the later Glastonbury Festivals. Following the violent suppression of the 1974 event, he and Sid Rawle were imprisoned to prevent the organising of a 1975 festival. Dwyer was imprisoned again attempting to organise another Windsor Free Festival in 1978, which did take place at Caesar's Camp nearby.