Hair, Gielgud Theatre

Who would have thought that the self-described "American Tribal Love-Rock Musical" better known as Hair would have proven over the years to be such a tricky customer? A defining template of the 1960s (the original cast album was one of the soundtracks of my youth), this counter-culture mother lode has spawned more cheesy revivals than some people have, well, hair.

So the first thing to be said about Diane Paulus's Tony-winning Broadway reincarnation as it hits Shaftesbury Avenue is that her exceedingly smart production honours the material with the same mixture of passion and fury that first sparked Hair before its current director was even born. This is a venture borne out of love and it will land even more fully in London once its hugely welcome Broadway cast has settled in - and simmered down.

This week's outing to Hair marked my third acquaintance with what has been a break-out production for Paulus, a 2009 Tony nominee for best director who now runs the American Repertory Theatre in Cambridge, Massachusetts, long one of America's most admired regional playhouses. But there's nothing remotely parochial about Paulus's vision of a piece whose whole really is better than the sum of its disparate, sometimes chaotic, always musically energising parts.

Sure, the book of Hair is thin and sketchy and the first act is more or less a song cycle that after the interval gives way to a Vietnam-era phantasmagoria where Paulus's skills really pay off. And yet, by restoring to Hair the sense of a happening that operates by its own, (literally) audience-embracing rules, Paulus soon routs all fears that the show is being delivered in inverted commas. Feel the love, the production dares to ask of both actors and audience at every turn. And in the final tableau, feel a generation's grief, as well.

That effect was palpable when I first caught this Hair in an al fresco version in New York's Central Park two summers ago, pre-Obama, where the references to "a dying nation" tallied with a Manhattan audience shell-shocked from two terms of Dubya and from the sense that the liberation powering Hair had somehow gone into terminal lock down. Catching the show again last spring on Broadway, where it's still running with a second cast, I saw that the tone had shifted from lamentation to celebration. Barack Obama was in the White House and, though America was (and remains) at war, hope no longer seemed a silly or futile word.

In London, where Hair has in fact had two previous revivals in the past 20 years, this staging has a different feel to it yet again that has to do with its American company functioning as cultural ambassadors to a degree rarely encountered before. (Never in my experience has a Broadway musical cast crossed the Atlantic wholesale, ensemble included.) So, can you blame them if at the final preview, many of the "tribe" seemed to be on some sort of adrenalin-fuelled overdrive? The result made for an evening perhaps a wee bit overdetermined to blow us away; check in with the same company before too much longer and I fully suspect that a less pushy Age of Aquarius will have dawned anew.

That said, Galt MacDermot's music is an enduring glory, without which the likes of Rent, Spring Awakening, and Broadway's currently previewing American Idiot would doubtless never have happened. Knockabout, rude, trippy, and on occasion transcendent, MacDermot's flits between Tom Lehrer-style pastiche and blissed-out meditation, karmic musings and, in "The Flesh Failures", a wrenching cri de coeur. The appeal to the moon that opens the show may never again have the resonance that it had in Central Park under a moonlit sky, but "Aquarius" kicks off a tirelessly wonderful score whose highlights will vary from person to person. I am, as ever, in thrall to the ruminative "Frank Mills" and Allison Case's piercingly sweet delivery of it, and Andrew Kober, doubling as Dad and Margaret Mead (hey, why not?), does better than ever by "My Conviction": a falsetto-filled paean of sorts to the very "flamboyant affectations" that Hair is about.

What Hair is even more about is community and togetherness amid an affectionate yet fearful set of young New Yorkers for whom love is sacred and war obscene. It's to Paulus's credit that she never sentimentalises an assortment of folks who can be very far from saintly, not least Will Swenson's now nearly rabid Berger, a horndog anti-hero whose casual cruelty prompts his adoring Sheila (strong-voiced Cassie Levy) to let rip with "Easy To Be Hard".

The tearaway from the tribe, of course, is Claude, the anglophile from Queens who quotes Hamlet and does the unthinkable in shearing his golden locks to go off and fight in 'Nam. Limber of both body and voice, Gavin Creel was remarkable in the role in New York and he's even better here, a cherub-faced emblem of the confusions of an age that finds Claude in exultant mode one minute (the rousing first-act "I Got Life"), in terminal despair the next. Hair on one level is a party, as is reflected in a set from Scott Pask that turns the Gielgud into an environmental arena allowing ample opportunity for the performers to get up close and personal with the house. But its jubilation comes tempered by pain, as one might expect from those who call out for, or fly too close to, the sun.

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