Courtney Barnett interview: The Melbourne singer-songwriter is the voice-of-a-generation

The day before I interview Courtney Barnett, she and her band perform a "guerrilla gig" outside Camden Town Tube station in north London. Under a slate-grey August sky, they run through her latest single six, seven, eight times while it is filmed for a promotional video. Barnett, a 27-year-old Australian, lip-syncs the first few renditions, giving the performance a strange, muted quality, but she remains animated and unperturbed in spite of the rather peculiar demands of the occasion. Her eyes twinkle, and, peering out from beneath her unbrushed hair, she has a cherubic smile.