By Chris Heard BBC News Online entertainment staff

A triumphant Brian Wilson has performed his great "lost" masterpiece Smile live for the first time.

Wilson's UK Smile shows have been long-awaited by fans

The prevailing mood was nervous excitement as the clock ticked down to Wilson's second UK show at London's Royal Festival Hall.

Expectations were high among fans milling around the bar as reports filtered through of a five-minute ovation for his live Smile debut the previous night.

Wearing their newly-bought �24 Smile T-shirts and clutching programmes (a snip at a tenner), the generation-spanning audience filed - smiling, mostly - into the auditorium.

A stage curtain dropped to reveal the 61-year-old Wilson - all in black, his grey hair swept back - perched on a stool, flanked tightly on all sides by his 10-strong backing band.

Wilson, whose live career has been dogged by stage fright, sat stiffly and seemed ill at ease as they worked through a few lame jokes and forced grins - presumably aimed at least in part at relaxing the genius-in-residence.

Wilson (left) made Smile without the other Beach Boys

But just as it was danger of descending into down-home parody, the a capella harmonies began and - thankfully - you knew that Brian Wilson was in the house.

What followed was a treat as Wilson visibly loosened up with a few of his earlier compositions, among them the beautiful In My Room and his songwriting genesis, Surfer Girl.

A few tunes in and he became as animated as he would get all evening, waving his arms from side to side to the rhythm, by now centre-stage at his Yamaha keyboard.

Wilson re-emerged after an interval, his backing musicians from LA band The Wondermints augmented by a string quintet and a full brass section. It was Smile time.

And so the full suite of songs from rock's unreleased masterpiece - Wilson's "teenage symphony to God" - was unfurled in its considerable glory, for only the second time.

Wilson has re-emerged with his legend intact

Beginning with the close-harmony singing of Our Prayer, the excitement built with an epic, multi-section take of Heroes and Villains - a mini-symphony in itself distilling Wilson's musical vision of the old Wild West, complete with saloon bar pianos, horses' hooves and native American chants.

Over the following half hour, the Wilson credentials were all in evidence: Cabinessence with its extraordinary soaring pop-operatics; the playful Vege-Tables (was that a green pepper being tackled by the backing singer?); and the majestic melancholy of Surf's Up.

With a nod to Smile folklore the five-piece Stockholm Strings and Horns donned fire helmets for the Elements suite. The legendary sequence climaxed with a celebratory Good Vibrations.

There were few surprises for anyone familiar with the many Smile bootlegs or the Beach Boys box set - merely the delight of hearing the album as a coherent whole in the way its 24-year-old prodigy had intended 37 years earlier.

Like the Pet Sounds shows of two years ago, much of the pleasure derives from the precision and note-perfect replication of Wilson's intricate melodies by The Wondermints, led by chief Wilson devotee Darian Sahanaja.

The Beach Boys made some of the 1960s' most durable pop hits

It all resulted in more ovations than a Tory party conference, including one reserved for Wilson's revered Smile lyricist, the silver-haired Van Dyke Parks.

Even without the night's centrepiece there was plenty to enjoy as Wilson reeled off some of the 1960s' most durable hits - California Girls, Help Me Rhonda, God Only Knows, Do It Again.

But this was no nostalgia show; rather, a relevant contemporary reading of a rock opus, performed by a much-loved figure recognised by generations of fans as one of the finest musicians of his time.

Nearly 40 years after being pilloried by fellow musicians and rejected by record label bosses, Wilson and Smile have re-emerged triumphant.

And like many great artists misunderstood and misrepresented in their prime, Wilson has proved - with courage and a unique modesty - that he was ahead of his time.