Short of handing out little bags of cake at the door, Mika Penniman did everything possible to turn his latest London show into an eight-year-old's birthday party.

Fancy dress was the preferred style on and off stage. The crowd was dotted with cowgirls, flappers and fairy princesses. Lewis Carroll's Alice skipped around handing out lollipops, and one man squeezed himself into a helicopter made from balloons.

Gallery: Mika in concert

There were bubbles, streamers and confetti explosions, generating an even greater visual feast than the one already offered by the courtyard of Somerset House - a stately, grandiose space that this campest of performers described as "frou frou".

He was playing halfway through Somerset House's annual series of summerconcerts, an all-too-brief season that also includes gigs by Black Rebel Motorcycle Club, Amy Winehouse and Hot Chip. It was the 23-year-old's first time on the bill, but he has been here before. He may now have a number one album and two, soon to be three, hit singles to his name, but it is an indication of the rapidity of his ascent that just over two years ago he was working at Somerset House as a waiter.

He certainly celebrated his triumphant return, spinning, skipping, squealing and eventually stripping off his shirt to batter a metal dustbin at the climax of Love Today. Tireless exuberance is his chief quality, as depicted in number one single Grace Kelly, which relates his exhaustive attempts to appeal to record company executives in the days before Scissor Sisters had proved that theatrical pop could sell. Some sickly sweet tunes, such as jaunty showtune Billy Brown and playground chant Lollipop, made it possible to see why his early approaches were spurned. Songs this catchy sound best the very first time you hear them, but after 10 months of touring they felt much less fresh.

His ballads strayed dangerously close to schmaltziness too. Any Other World sounded like something from the boring bit of a Disney film, although the rarely aired Over My Shoulder revealed an intriguing dark side untapped elsewhere.

Often, though, it was impossible to resist him. Big Girl (You are Beautiful) added an infectious bassline and funky guitars to the Size Zero debate, while Relax, Take It Easy was a classy house tune that demonstrated his Royal Opera-trained falsetto to best effect.

The colourful crowd lapped it up in its entirety. They had come for a party, and he gave them nothing less, and nothing more.