I guess no matter how experienced we are in this business we never stop being drama students, in a rehearsal room or as part of an audience we're always studying drama. This revival of Hair provides a lesson to us all in exactly how to successfully present the American musical in general and this musical in particular.

Diana Paulus directs with such simplicity and clarity the message of the piece emerges with all the freshness and power as must have been so refreshingly apparent when it first burst through a dopey haze in 1967.

I'd always thought you had to be on something to get it, that it was futile to try and make sense of it as clearly the writers were high as kites when they cobbled it together, that the whole thing was an elaborate joke at the expense of nice middle class people, like my dad, who bought the album with it's iconic afro logo. Here the genius of the piece is as plain to see as a ban-the-bomb banner. It screams relevance and parallels with Afghanistan and Iraq precisely because it remains in period without recourse to the unsubtle anachronisms of Bush/Blair face-masks and the like as we suffered with the misguided ‘updated' revival at the Gate recently.

This isn't just theatre this is a spiritual experience - when did you last see that on a Number One tour?

Choreography should be like a film score – if you become too aware of it, it's not doing its job. Here we get an unselfconscious deceptively “unrehearsed” fluidity and economy by Karole Armitage where every movement means something and serves a purpose. It's like watching giant origami, a precise and perfect fold here, another one there and then suddenly, a beautiful dragon!

This show should be compulsory for every choreographer in the country, and musical theatre actor whilst am at it! Because here we get and not just from the star vocalists like the Dionne of Sasha Allen or the swaggering presence of Darius Nichols as Hud but from everyone, appropriate playing which serves the piece. It has charm and character and is engaging, truthful and sincere. Nothing knowing or campy. This isn't just theatre this is a spiritual experience - when did you last see that on a Number One tour?

You must see this, go see Gavin Creel (Claude) and Will Swenson (Berger) deploy their technique and skill with such expertise as to make it look as if they've just stepped untrained off the street. Marvel at their relationship at the big heart of this piece.

So a total joy with much to learn from and which ultimately and devastatingly teaches us that in over 40 years humanity has learnt nothing.

Gielgud Theatre
Shaftesbury Avenue
www.hairthemusical.co.uk