When thick traffic and bad weather forced Joni Mitchell to cancel her appearance at Woodstock, she watched the seminal 1960s festival on television in her New York hotel room.

Thirty years on and Woodstock 99, the anniversary concert, is back on TV. But this time it is strictly pay-per-view - $60 (£39) for the full three days.

Jimi Hendrix headlined at the original concert

The 1969 event buckled under the sheer weight of numbers. Almost 500,000 turned up, prompting the organisers to abandon ticketing and let fans in for free.

As the heavens opened, the roads leading to Max Yasgur's farm near the town of Bethel in upstate New York turned to mudslides. The area was declared an official disaster zone.

Times are a changin'

The anniversary festival is a textbook example of 1990s event management.

Tickets are $180 (£115) a throw - more if you want a full package deal. Merchandise is everywhere and its distribution is controlled by licensing deals.

Joe Anderson, stagehand at Woodstock: "They didn't really need security. They didn't have any problems"

The original "who needs cash?" spirit has taken a bizarre twist with a Woodstock platinum credit card, which has a $100,000 (£64,000) spending limit.

Clearly this is no sentimental journey into the past.

Immortalised on vinyl - the Woodstock album

Amid all the blatant profiteering, it is easy to lose sight of why the 1969 event has become forever immortalised as the ultimate rock festival.

Woodstock was not the first "everything-goes" outdoor spectacular. The Monterey International Pop Festival predated it by two years, catching the West Coast hippy vibe with acts such as Jefferson Airplane, Janis Joplin, Jimi Hendrix and Ravi Shankar.

But Monterey was a stage-managed affair - there were even rows of chairs set out for some of the 50,000 crowd.

Spirit of rebellion

By the summer of 1969, rebellion was a youth movement in the United States.

The horrors of the Vietnam war were being exposed in the media and many young people - including icons such as world heavyweight champion Muhammad Ali - risked prison in their efforts to avoid "the draft".

Joe Anderson: "The nurses and doctors all put on clowns' noses"

Woodstock was more than a music festival, it represented a common cause for the disillusioned. Where politics had failed, music could triumph.

Joe Anderson, a stagehand at Woodstock 69, said: "People thought it was a cultural movement that would spread and grow.

Three days of peace and music - the Woodstock poster

"A lot of us thought at the time that it was going to change the future. It was a time that the youth of America felt like they were one big cause."

Psychedelic drugs

One of the unifying factors was drugs. Marijuana and LSD were openly ingested, causing a shedding of inhibition which led to many stripping naked.

Joe Anderson: "People thought that it was a cultural movement that would spread and grow"

The laid-back communal spirit was epitomised by compere Wavy Gravy's rasping wake-up call: "What we have in mind is breakfast in bed for 400,000."

Despite the largely white, middle class audience, Woodstock presented a cosmopolitan mix of stage acts - protest songs from Joan Baez and Country Joe McDonald, Fifties jive from Sha-Na-Na, funk from Sly and the Family Stone, blues from Ten Years After and white soul from Joe Cocker.

Will Conway, who was in the audience back in 1969, said: "The music was ongoing through the nights, and I remember waking up to Hendrix's Star Spangled Banner and being duly wowed.

"Janis [Joplin] was awesome, belting out blues in her purple tie-dye velveted rasping voice. The people were a flood of ecstatic reverie, melting into each other's rainbowed bodyminds."

Then the rain came

Mr Anderson says spirits were so high that when rain came on the first night, it bonded people closer. Downpours continued throughout the weekend.

"It was summer time, you were wet, the music was good, it didn't matter," he recalls.

The concert was so peaceful Mr Anderson was relieved of his security duties and went to help in the medical tent.

"For the people who took [acid] for the first time it was confusing for them.

Nurses in clown noses

"The doctors didn't know how to deal with people so they were nervous and then someone came along and told the doctors they should make it fun.

"The nurses put on clown noses and clown hats and after a while it wasn't an uptight scene, it was people laughing."

By the end of the three days, many of the fans thought the Woodstock spirit of peace and love would win over America.

But, before the 1960s were out, came Altamont - the Rolling Stones concert which seemed to draw a similar crowd of hippy music lovers.