Polar Bear @ Mostly Jazz Festival, Birmingham

Opening with a deep, rolling swing, effortlessly morphing into contrasts of snappy and smooth, the current Polar Bear are a subtle topographical endeavour. Assertive, perhaps aggressive, it's the show opener and it’s a f**king festival.

"Hello, how are you? It's a nice day, isn't it?" speaks a softly-spoken Sebastian "Seb" Rochford. His voice is in stark contrast to his music, but when there are a thousand or so people lounging by a lake listening to jazz, the highly conceptual sounds have a heavy hypnotic effect on the blissed-out, sun-baked minds of the crowd. His voice brings the audience to, before the music takes hold again.

What's that baseline? Is that Gorillaz’ ‘Stylo’?(!) The success of this group could be put down to their comfort at accepting cutting edge popular culture and running with it unabashed by theory or convention - which means it must be time for the balloon solo.

Next is another rocksteady skating track, broken down to staccato slap bass and ambient sounds provided by Leafcutter John, the aforementioned balloon player and laptop music nerd.

Egged on by the potential and possibility of the musicians, song structures frequently take on an explorative ethos. As Rochford turns to his bass player from his raised drum kit there's a degree of intimidating authority, that: despite the music ascending into freeform textures and unstable territories, it will never lose its purpose. Occasionally he will break the silences with a truncated march or a straight-up drum pattern.

With much of the textual movement being so controlled, crescendos, patterns etc. few parts of the set seem improvised, or at least, there are strict markers in place for each musician to aim at giving the show a focus.

The set ends with "a quick one". It's testament to the hi-nrg ethic set by Rochford and his team. Right, enough of that, there's a football match, ahem, festival on.