Have Kaiser Chiefs lost their famous sense of fun? First, Yours Truly, Angry Mob , a second album littered with issue lyrics. Then a rash of interviews in which the Leeds-based band bemoaned their perceived place in pop, rather than rock. And before their headline set at the Hyde Park Wireless Festival, a ban on inflatable toys by a singer once happy to dance with a green dinosaur and frolic alongside a lobster.

Yet there was no sign of a serious side when Kaiser Chiefs’ leader Ricky Wilson halted the intro of the opening number Everyday I Love You Less and Less to peel off his jacket provocatively and leap from a small set of stairs. Initially it felt like a vintage performance — the crowd hijacking every chorus, mass overhead handclaps and Wilson clambering down to the crowd barrier to be held aloft by security guards.

The recent single Ruby certainly had the silly, singalong quality that two years ago shot Kaiser Chiefs to the top of the Britpop tree and helped their debut album, Employment , to sell close to three million copies. But it was as subtle as a brick and its repetitive chant trod a fine line between cheerfully cheeky and ludicrously laboured. Moreover, it played up to a section of the crowd who wanted basic, Oasis-like anthems and when they didn’t get them took to throwing pints of beer.

A guest appearance from a member of the Japanese synth-punk outfit Polysics briefly brought the fun back. In a bright orange boiler suit that made Wilson’s ensemble of buttoned-up waistcoat over denim shirt look positively plain, he yelped, howled and, yes, star-jumped. It was an injection of pure joy that soon faded. For the next half an hour, Kaiser Chiefs struggled to sparkle.

They rallied towards the end of the set with an Angry Mob that ignited a genuine passion in Wilson. For the first time he looked like a real rock star, rather than a puppy eager to please. For I Predict a Riot , he climbed the side rigging and bounced with his mike stand, but it was when he stood still, framed in lights and dry ice, that he truly commanded the crowd. If Wilson wants to be taken seriously, more singing as if he means it is required. Whether his fans have him down for a different future is probably out of his hands.

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