What's this? A palpable frisson of excitement at the prospect of attending a Keane concert? This unlikely sensation was the result not of a decent second album, or the grandiose surroundings of Alexandra Palace, but the first genuinely shocking celebrity rehab story in a very long time.

Singing Scout leader Tom Chaplin had been overindulging in sherry and checked himself into the Priory in August.

"I've been having to deal with an increasing problem with drink and drugs, and the time has come to get the professional help I need to sort myself out," he said at the time. It was like finding out Phillip Schofield is a Satanist.

A US tour had to be pulled and the band's relentless globe-conquering was postponed for a short while.

But now that the trio are back on the big stages, Chaplin's newfound humility does not outweigh his frontman's confidence, and the success story appears to be back on track, on the surface at least.

While it may not be wise for him to resume the intensity of the touring lifestyle so quickly - depending on how serious his problem really was - here he was joyously in his element, whirling around, jousting with his microphone stand, glad-handing the crowd and revelling in the attention. "Sing it with us, London" he bellowed before the titanic chorus of Everybody's Changing, and London sang.

He may not say much, but songwriter and pianist Tim Rice-Oxley was just as watchable, using his stool as a base from which to launch himself, arms flailing, head shaking, legs tensed as though on a starting block. As the only source of non-vocal sound aside from drummer Richard Hughes, he has a huge job, and his band don't get enough credit for how radical it is to create their rich music with just these two instruments.

Chaplin did give a basic strum to an acoustic guitar on Your Eyes Open, but otherwise it was all Rice-Oxley, feeding his keyboard through effects pedals to create improbable new sounds on irresistibly catchy tracks such as Is It Any Wonder? and Crystal Ball.

Most intriguingly, the pianist has written some telling lyrics for his bandmate to sing: "Fool, I wonder if you know yourself at all" on the haunting Hamburg Song, or "A slap in the face for you now/Just might do now" in Leaving So Soon? Singing these words every night might be the best therapy of all.