The backlash against the Magic Numbers has already begun, with many music critics claiming the quartet’s expiration date was some time ago, at any rate before the release of their second album, Those the Brokes, last month.

It’s a familiar tale: band releases brilliant debut album full of feelgood pop melodies, band is nominated for Mercury prize before recording a second album that is unlikely to be considered as good as the first.

But while there doesn’t seem to be the same universal appreciation of their harmony-driven, cartoon pop as there was this time last year, the Magic Numbers are as good as they’ve ever been.

Those the Brokes is a fine album. It may lack some of the obvious hits of their self-titled debut, but it is a more coherent record and less of an attempt to please its audience with catchy choruses. It is, put simply, a grower.

As fast as their acceleration to stardom has been, they look and sound like a band who have been playing together for decades, but with the enthusiasm that comes with still being relatively fresh to the scene. It’s difficult not to be enchanted by their 1960s-style charisma, the slightly unruly haircuts and the hirsute charm of the two male members of the band.

But on a visual level it’s the girls — the band is comprised of two pairs of brother and sister — who steal the show. The bassist, Michele Stodart, sister of the lead singer, Romeo, plays brilliantly and has the effortless rock poise of a young Ozzy Osbourne. Her harmonies with Angela Gannon are at the heart of all the group’s best moments and sound even better live than on record.

When they launch into Forever Lost and Love’s a Game — both hits from the first album — the swelling chorus of their voices falls like a warm blanket over a Barrowland crowd clearly intoxicated by the musical buzz.

After all, this is a hands-in-the-air high in the form of a harmony pop group the like of which has not been seen since 1960s bands such as the Mamas and the Papas and the Beach Boys.

Love Me Like You, a song that is likely to remain their signature tune for years to come, is delivered with a delightfully adolescent energy culminating in a round of applause, presumably for herself, from Stodart.

Of the newer songs, Take a Chance is the most obvious hit and every bit as poppy and thrilling as anything on the first album. With its hypnotic refrain, “Take a chance on the woman who lets you”, it’s another fine example of Stodart’s willingness to pour out his heart for a song.

But, curiously, the night hits a high note when Gannon takes over lead vocals for Undecided, a soulful, blues number that demonstrates the considerable scope of her vocal range.

And what a voice it is. Gannon has a pair of lungs and ragged rasp to match Janis Joplin and the earthy, ethereal tone of Aretha Franklin. It might be the best-kept secret in the Magic Numbers’ arsenal. At any rate, they are a band full of surprises.

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