In June 1971, Kerr staged "Glastonbury Fair", along with Arabella Churchill and some other friends. Glastonbury Fair originated the use of the name 'Glastonbury', the June date, and the pyramid stage, inspired by the work of author John Michell. The position of the stage was dowsed by Kerr according with his belief in ley lines, and the 'Glastonbury' part of the festival's name was introduced.
Kerr was inspired to put on a free festival after his experience at the commercial Isle of Wight Festival in 1970. His original motivation for staging a free festival was outlined in a leaflet published at the time:
To mark the 40th anniversary of the Glastonbury Fair, at the 2011 Glastonbury Festival Kerr organized a 'Spirit of 71' stage, with a number of the original performers. 'Spirit of 71' was also incorporated into the 2013 festival
In his book Groovy Old Men author Nick Baker says of Kerr:
Born in Ewell, Surrey in 1933, Kerr's childhood during the war years was spent in south Oxfordshire, but he was evacuated to Ilfracombe for a period, and immediately afterwards the family was farming in the area. He was at school at Radley College. He spent his National Service as a stores assistant at Portsmouth in the Royal Navy, in which his father also served.
For ten years following 1958 he was employed as personal assistant to Randolph Spencer Churchill, who was writing the official biography of his father, Sir Winston Churchill.
After organizing Glastonbury Fair in 1971, Kerr continued to manage the Glastonbury Festival site up until the mid 1980s.
In 1992 Kerr put on the Whole Earth Show in Dorset, promoting organic agriculture and sustainable technologies. BBC Radio 4 carried the first wind powered broadcast from the show, while Tibetan priests blessed the site and those present.
He has been a consistent advocate of the benefits of aerobic composting, and has spoken on TV and radio about composting and the potential of compost funerals.
Kerr spent his last years in Pilton, Somerset, home of the Glastonbury Festival.
Kerr's autobiography Intolerably Hip: The memoirs of Andrew Kerr was published in May 2011. A review in the Daily Mail referred to its "slightly mad authenticity".