He's put the drink and drugs behind him, but Rufus Wainwright remains a diva. Spying two empty seats near the front of the stage, he demands they be filled. "I'm a big-time celebrity," he says, with only a dash of irony. "Now I can be completely unreasonable. It's a necessity."

In reality, Wainwright is far from a household name, and his operatic torch songs are cult classics rather than hits. But his first post-rehab album, Release the Stars, should change that: more accessible than 2005's Want Two, it swaps elegant strings for horn; constant, fragile longing for songs about love and relationships. Mirroring the sequin-bedecked US flag hanging behind them, Wainwright and his seven-strong band wear stripey suits and sparkly brooches. As he eases into Going to a Town, his weary goodbye kiss to the USA, it is his honesty and sincerity that dazzle. "From the sublime to the sublime," he comments, but the decision to play Release the Stars in its entirety says more about his ambition than his showmanship - and means Wainwright rarely leaves the ground.

But when he slips into tight-fitting lederhosen and revisits his past, he soars. Singing the Irish song Macushlah without a microphone, his pure, clear voice swells and trembles on cue. Brass and bass buzz around him on the sprawling Beautiful Boy, and he is alone on stage, intense and intimate, for Pretty Things.

Although Wainwright is now very much in touch with reality, Judy Garland remains his fantasy figure. Her songs Foggy Day and If Love Were All reveal Wainwright's feminine side. Clipping on diamante earrings and applying red lipstick, he dons Garland's iconic uniform of fedora and long suit jacket to perform his version of Get Happy, while the band, in tuxedos, jump around him. If anyone else tried squeezing into Garland's heels it would be parody, but Wainwright makes it a homage both to her and to the legitimate star he is about to become.

· Ends tomorrow. Box office: 0870 060 6628.