Having started out busking outside our cultural institutions, Portico Quartet are now warmly welcomed into the inner sanctum.

Their supposedly token spot as the jazz act on the 2008 Mercury Prize shortlist has led to a serious upswing in their gigging prospects.

The secret to their accessibility is the hang, an obscure Swiss instrument played by Nick Mulvey that gives them an instantly recognisable sound.

Mulvey had four of them, which did not hang but perched on spindly black legs like War of the Worlds invaders. I didn’t notice him using the fourth one — perhaps it was a barbecue for afterwards.

Sounding similar to a steel drum but softer and less sunny, they gave an alien element to the more traditional backdrop of Duncan Bellamy’s tickled drums and Milo Fitzpatrick’s plucked, strummed and scraped double bass.

Three pairs of feet tapped out the same beat while Jack Wyllie, with his comically tiny soprano saxophone, stayed still, free to float and dive among the other sounds. Mostly it washed over rather than demanding attention, and certain songs seemed simply to fizzle out, but it was undeniably a beautiful sound.

If there had been a hat in front of them they would have made plenty.