Athlete, Union Chapel

They’ve called the tour "The Hits - Stripped Back". But they weren’t all hits. More importantly, they weren’t merely stripped back either. They’d evolved. The band’s ability to write quality anthemic indie rock is undeniable. But so is the fact that sometimes it’s hard to distinguish them from a slew of other bands with awkward names and characterful voices, like Feeder or Embrace. Or Elbow. And Elbow have stolen the market share. So where does this leave Athlete? It leaves them taking a step back from the pop game, and getting excited about the sonic possibilities of making music together.

If last night was a retrospective, it was also a celebration. The stage set was simply decorated with a selection of bizarre standard lamps that looked like they belonged to someone’s grandma, but which we were told the band had actually bought on eBay. Singer Joel Pott and bassist Carey Willets were more conventionally dressed in shirts and jeans. There was something very wholesome-looking about the two. They looked like in another life they might have been doctors. The crowd, however, were completely impossible to characterise. There seemed to be very little uniting them. Men, women, young, old – it was almost as if 800 people had been plucked off Islington High Street at random. But they did all have one thing in common, they were somewhat in love with the band.

From the moment Pott strummed the first chords of “Half Light” it was clear that the band had decided not to give their songs a simple "unplugged" treatment. Instead they treated them like covers, giving them an identity separate from that on the record. And it made for some tasty offerings. In fact, the further the band took the songs away from the original, the more interesting it got. The synth reworking of “Westside” sounded like The Postal Service crossed with Metronomy. The drum machine and effected piano gave “The Outsiders” a sinister turn. “Tourist” was given real edge and the most remarkable version was “El Salvador”, improbably recast as a Mummers-esque dreamscape.

But with so many big songs on offer and so many people after a good time, there was also something of the cabaret about the evening. In fact, there were times when it could as easily have been called “An Audience with Athlete”. Pott showed that he has a possible alternative career as a comedian. Particular members of the audience were identified at the beginning of the night, and returned to throughout. “Superhuman Touch” became a clapalong, “You Got the Style” a singalong. When “Wires” appeared we all stood up to give it a sense of drama. “Chances”, that closed proceedings, had the entire room swaying, arms in the air.

And it all sounded immaculate. From the anthems to the evening’s most poignant moment of fragile, spectral beauty, “Flying Over Bus Stops”, there was not a sound gremlin in sight. Frequently at the Union the drums and bass disappear up the bell tower or bounce off the buttresses, but last night everything was warm and full. Just as it should be. Pott was in particularly fine voice, especially on solo spot "The Getaway". What can seem an exaggerated vocal style on record was toned down, and he seemed to be injecting more thoughtfulness into the words without losing any of the emotion. The rest of the band performed with equal measures of precision and heart. Although nominally acoustic, actually almost everything was plugged in. What it was, was chamber-pop, in its most literal sense, and the stripped-back approach served the songs better than their usual, fully produced sound.

Athlete have frequently found themselves on the cusp of being a big act, but never quite made that final sprint for the line. If they’ve found a niche now, it’s a pretty happy one. As Elbow have shown, thoughtful guitar bands can become enormous just by a couple of tunes catching the mood of a particular audience. Athlete have already shown that they can write anthems and express emotions on a grand scale. Last night they showed that they can do intimate just as well. Don’t be surprised then if album number five becomes huge.

• Find Athlete on Amazon
• Download Athlete on iTunes
• Book tickets for Athlete, on tour until 2 August

Watch Athlete perform "Black Swan Song"