And if they could best make their point by defiantly stripping off in public, well, who cared if people were shocked?
When the Broadway rock musical Hair first opened in London’s West End in 1968, it was to a background of protest against the Vietnam war and authority, whether parents or governments.
Party time: Elaine Paige and Cameron Mackintosh in 1991
It made stars of young unknowns like Elaine Paige, Paul Nicholas and Oliver Tobias. Elaine even gave a helping hand - literally - to another cast member, Gary Hamilton.
‘I had to strip off, along with the rest of the cast, for the show’s big nude scene, ’ she recalls.
‘I was only 18, very middle class and terrified. Gary said he’d help me through it by holding my hand for moral support.
‘When it came to the big moment, where we all had to emerge naked from under a canvas, I reached out for him, only to find that because he’s very tall and I am very short, it wasn’t his hand I grabbed!
‘In the spirit of the show - free love and all that - my mistake worked well. I was horrified, but Gary wasn’t complaining.’
NOTORIETY? I WAS NO REBEL
Paul Nicholas played a leading role as a hippy torn between going into the Army and fighting for his country in the Vietnam War, or remaining with a group of drop-outs living on the streets of New York.
‘It was my very first show. The day I went for the audition, there was a very enthusiastic young man in glasses who showed me to the stage and was obviously kind of assisting on the auditions.
'That young man was Cameron. It changed my life without a shadow of a doubt. It did give me an opportunity to find in life what I wanted to do. Although I was in showbusiness, I wasn’t really satisfied trying to be a singer. That wasn’t enough for me, but I didn’t quite know what was. So for me it was a life-changing experience.'
It may have been all about free love and letting it all hang out, but it gave him the kind of stability and respectability that the show was rebelling against.
He says: ‘I met my wife Linzi in the show - we have six children and 12 grandchildren.’
Now Hair is about to be re-staged here, complete with its infamous nude scene, and although the central theme - and the war - is resolutely unchanged in the show, a spookily similar set of modern events make it just as relevant today as it was 42 years ago.
‘There is a worldwide protest against the war in Afghanistan, just as there was against Vietnam, ’ says impresario Sir Cameron Mackintosh, who is importing the show from Broadway, where it has been enjoying an award-winning renaissance.
‘But Hair is more than an anti-war show. There is genuine worry about the future and our survival, whether it’s endangered by conflict, greedy bankers or climate change.
'Even in the Sixties, these were major social concerns for young people, and the question they were all asking was, where do they go now?
‘We’ve got all these graduates pouring out of universities and with the economic downturn and the world in turmoil they are wondering what they’re going to do with their lives, which is the problem faced by the leading character in Hair.
‘The songs reflected many emerging worries. Big Brother government, the potential data-gathering ability of computers, electronic surveillance, corporate greed, pollution - everything that has since come true.’
He adds: ‘The younger generation were turning to drugs like marijuana and LSD and their parents were desperately worried about the effects.
'Those worries are still there and so are those drugs - but a lot more have been added, from cocaine to meow meow. Nothing has changed.’
Elaine Paige says she wasn’t surprised the musical became a cult show -although now she wonders if they were all being naive in believing that their on-stage protest would change things.
‘My father warned me that nothing would change, and he was right. We really did believe we were going to change the world, though.
‘It made me realise that one should live for the moment, and since then I have tried to do that. I think it did change my ideas on things like that and you’ve got to remember I was very young.
'I came from a household that wasn’t too strict, but there were certain disciplines in the house, in the way that my parents expected us to live.
‘I wasn’t allowed out for all hours at night. There was a certain respect expected towards my elders. All the morals and the way I was brought up were from a different generation that came out of World War II.
The show’s co-writer, Gerome Ragni, joined a Christian cult and gave his multi-million-pound earnings to the radical movement the Black Panthers
'And there we were in the Sixties kicking against it as a load of old nonsense.
All we wanted was to have our freedom and allow people to be what they wanted to be.
‘All very well, but I came to realise that it probably doesn’t work like that. And in hindsight, now that I’m the same age as my parents were then, I don’t think that trying to get rid of the rules and regulations we were trying to break down has necessarily been a good thing.’
If anything, says Sir Cameron, the anarchic messages of Hair are even more relevant now than they were back in the Sixties.
And he should know, for he was a junior backstage assistant during the original production.
‘It was the first musical from the streets, ’ he recalls. ‘There was this movement of flower-power, peace and love. The Beatles were doing Sergeant Pepper.
‘Social barriers were being broken down. Authority was being questioned, there was a lot of civil disobedience, with young Americans refusing to be conscripted into the military to fight a war they believed was none of their country’s business.’
Sir Cameron adds: ‘The people who flocked to the show were not the usual mainstream theatre-goers - instead they were kids, of student age, with their lives about to open up in front of them.