Glastonbury first opened its gates in 1970, when T Rex headlined
Glastonbury founder Michael Eavis says the music festival will never lose its licence because it has become too important to the local economy.
"The local economy gets £100m a year," he told Radio 4's Desert Island Discs.
"So there's no discussion about not allowing the festival a licence any more. They won't stop it now."
Glastonbury was last refused a licence in 2002 after surrounding villages raised concerns about crime. The decision was later overturned.
In 2007, Mendip District Council in Somerset agreed to a four-year licence, which secured the event's future until 2010.
"They're all on board now because everybody earns some money from it - there are seven farms I have to rent," Eavis added.
Eavis has been welcoming festival-goers to Worthy Farm in Pilton, Somerset since 1970.
EAVIS'S DESERT ISLAND DISCS
Children of the Revolution
Marc Bolan and T-Rex
Twelfth Street Rag
Pee Wee Hunt
How Great Thou Art*
Uncle John's Band
The Grateful Dead
I Threw It All Away
Stop Me If You Think You've Heard This One Before
The Stone Roses
Book: Blake - A Biography by Peter Ackroyd
Luxury: A mouth organ with instruction book
* Denotes the one record to be kept above all others
It now attracts 137,500 visitors a year, with the likes of REM, Jay-Z, Coldplay and Sir Paul McCartney among recent headline acts.
But Eavis told Desert Island Discs presenter Kirsty Young that he and his second wife, Jean, had agreed to close the festival in 2000.
However, Jean - who who was known as the "mother of Glastonbury" - died in May 1999 at the age of 60.
"We'd agreed we were going to retire. And unfortunately Jean never made it," Eavis said.
"So I was more determined to carry it on because I didn't have a girlfriend or anything.
"And of course all the kids were very keen on it. So it was like my new lady friend in a way, the festival."
During his appearance on Radio 4, Eavis chose several records by former Glastonbury headliners to take away to the notional Desert Island.
Among them were Marc Bolan's Children Of The Revolution and Stop Me If You Think You've Heard This One Before by The Smiths, who Eavis credited with transforming the festival with their appearance in 1984.
"We'd been having hippy stuff up 'til then, and suddenly we had the Smiths, who were very cool, and very fashionable.
"And it just changed the whole event. It suddenly became a big pop festival then."