Morcheeba, Somerset House, London

It was one of those dreamlike events. We were under the moonlit sky, and Morcheeba was taking us back to another time and place, when infant trip-hop collectives like Portishead and Moloko were still grooving mellow. The atmosphere was chilled and nothing much mattered.

"Oh yes! Oh yes!" cried a man beside me at the Summer at Somerset House gig, held in its splendid courtyard overlooking the river Thames. And oh, yes, they were that good.

As the evening wore on, the London skyline faded to a shade darker than blue, but the ambient light was enough - with the help of some powerful floodlights - to illuminate the breathtaking architecture of Sir William Chambers's 18th-century redesign of this originally Tudor Palace.

And when Skye Edwards, Morcheeba's impish singer, clambered up on stage, resplendent in a billowing red dress strikingly similar to the one worn by Marilyn Monroe in The Seven Year Itch, we knew we were in for something special.

Without hesitation, Edwards cracked a large smile and the first few lines of "Part of the Process" spilled out. The cheer from the crowd reached a crescendo, hovered for a while in the night sky and then, seemingly, drifted down river.

Edwards was off, and with that famous, enchantingly sexy whisper of a voice, she soon had the crowd eating out of her hand. To remind us that this wasn't the Skye Edwards Show, brothers Paul and Ross Godfrey, who complete the band, launched into a reggae-drum'n'bass-cum-trip-hop groove that was a clear signpost to their roots. It was delicious stuff.

By the time they had got round to the shamelessly poppy "Tape Loop", an early hit for the group, Edwards glowed with sweat, the tiny beads of perspiration reflecting off her black skin. "I'm hot," she quipped. Yes, it was hot: with daytime temperatures nudging 36C, the band could not have picked a better day to stage an open-air concert.

The evening - musically, at least - would become even more inferno-like. With everybody more than toasty warm, Edwards and the brothers picked up the tempo and sprinted through most of their back catalogue, with songs such as "Blindfold", "Let Me See", "Be Yourself", "Howling", "Slow Down" and the dreamy, hazy "Trigger Hippie", the band's first hit and the song that has become their signature tune.

The packed résumé was to remind us that Morcheeba have a greatest hits album, Parts of the Process, in the shops now. But they were preaching to the converted. "Hands up all those who have bought the latest album," enquired Edwards. In an instant, the courtyard was a sea of hands.

When the audience reached the choruses before Edwards could, she knew her evening's work was done. Such was the case with the final song, "Rome Wasn't Built in a Day". It became a devotional sing-along. But no one was complaining.