Although billed as an immersive staging, Jonathan O'Boyle's imaginative new production of Hair doesn't really do anything particularly new. Having the hippie tribe clambering all over the audience at times and inviting them up to dance on stage at the end is pretty much de rigueur in any version of this chaotic but undeniably powerful rock musical.

However, Maeve Black (designer) and Ben M Rogers (lighting) have really gone to town on transforming the venue into a late 1960s, bohemian, peacenik environment. It's a riot of garish colour, with teepees, scatter cushions, flags, stalls, flowers and incense everywhere one looks, and as the audience file in the cast are on the grass floor meditating in a circle. The concept is delightful and firmly roots the piece in its place and time. The production will even be hosting a couple of 'clothing optional' performances, which starts to sound less and less like a bad idea the longer one spends in the stifling heat of the Vaults' auditorium.

Although it builds up a head of urgent dramatic steam in its deeply moving final ten minutes, Gerome Ragni and James Rado's book has always been a bit of a mess - more a series of sketches around the idea of being an anti-Vietnam war protester than a coherent story. But O'Boyle's atmospheric staging goes some way to solving this by treating the whole thing as an elaborate hippie ritual. Less glossy and with a smaller cast than the last West End revival, this probably gets nearer to the original spirit of the piece, which combines a sweetly naive belief in the power of love with potent rage at the futility of war, to ultimately devastating emotional effect.

It's chief strength is Galt MacDermott's enchanting, melodic music - numbers like "Aquarius", "Good Morning Starshine" and "Let The Sunshine In" have rightly become classics, and they are magnificently rendered here by a terrific young cast and fine rock band.

This is very much an ensemble show but particular stand-outs are Andy Coxon as a puckish, strung out tribe leader, Jammy Kasongo performing a wittily disturbing parody of a minstrel number, and thrilling-voiced, saxophone-playing diva Shekinah McFarlane leading the company in the glorious "Aquarius" opener and later in a raucous paean to the joys of inter-racial sex. The singing throughout is exceptional, and William Whelton's inventive choreography achieves the impressive feat of looking simultaneously sharp and spontaneous.

Using a recording of a Trump speech at the outset is a rather obvious way of trying to pin modern relevance to the show and feels unnecessary, especially since it is never referred to again. Daniel Kramer's astonishing 2005 production at the Gate successfully updated the piece to a post-9/11 urban landscape and entirely dispensed with the hippie paraphernalia. This version is cuddlier, less confrontational than that, yet succeeds superbly on its own terms.

I defy anybody not to be moved by the raw emotion of the "Let The Sunshine In" finale where the tribe reconvene in the falling snow to celebrate their friend who has been drafted off to war, and to make a desperate plea for tolerance and kindness. It's a heartfelt, simple message that is as potent and urgent in 2017 as it was in 1967, maybe more so, and it packs a bigger emotional wallop than almost any other musical closing number that I can think of.

Hair runs at The Vaults until 3 December.