Simplicity is the key to success at the moment for First Aid Kit. On the face of it, there’s nothing especially remarkable on show here. Sisters Klara and Johanna Söderberg play a very straightforward folk music – simple melodies; glorious harmonies, it’s comfortingly familiar stuff. And yet, there’s something of an air of greatness about them.

Partly, that’s due to their charm on stage but mostly it’s down to Johanna Söderberg’s glorious, soaring voice. Her handling of Fleet Foxes’ Tiger Mountain Peasant Song is immaculate and seemingly effortless.

Much more than that though is the feeling that this is only the very beginning. The sisters are impossibly young (they are still chaperoned by their father who acts as soundman during their tours) and can only get better. Already, they are able to do the simple things stunningly well, once they begin to develop further and start to push the boundaries of their music, who knows what they will be capable of.

That autoharp which Klara is clutching might only be the start.