A police siren whirs in the background but Pat Pierce assures The Music there's nothing to worry about: “It's definitely not for us, it's for someone else – we've got a permit.”

Pierce Brothers – Pat and his identical twin brother Jack – have just clocked off after another successful day busking on Bourke Street, though if things keep going the way they are they might not need the 'day job' anymore.

By the time you read this the pair will have probably sold out a fifth and final night at Shebeen Bandroom, an incredible feat for an independent act that's received minimal radio airplay. “It's blowing our minds,” Pat gushes. “Hopefully if it takes off completely I can just spend my time surfing and writing music – I'd love to just do that.”

As well as offering the perfect platform to road-test tracks from their latest EP The Night Tree, busking has also filled the boys with the kind of captivating charisma that can win a room over in an instant. Pat agrees that it's helped the brothers engage the crowd better during their own club shows.

“When you're a street performer you just do everything you can to keep people's interest, and that translates directly to our live show – [Jack] will end up in the rafters!” Pat laughs. “The other day he jumped up and was hanging off the lighting poles on the roof, and the crowd was going mental, then I went under him and he dropped onto my shoulders and started hitting the roof. It's stupid twin things.”

That stupid twin thing though – that intrinsic connection – is something that brings so much both musically and personally. But even Pat admits it's hard to define. “On stage we know where the other one is going – we'll start jamming something out and we don't even need to practice it, we'll just go with it.

Playing every single day for four-to-five hours helps too. “It just gets easier and easier to make something up and have it not fuck up on us,” says Pat. “We can do something on the fly, but actually pull it off.”

Before they fell in love with folk and roots music, heavy rock was their poison, an influence of their older brothers. “Metallica was our first concert we went to, and we're folk musicians!” Pat exclaims. “But the first song we ever learnt to play – Come As You Are by Nirvana – we couldn't even hold an acoustic guitar, we had to put it on our lap. It was the early-to-mid '90s, so it was just that classic grunge stuff that got us started.”

Once they entered high school, however, Pat and Jack discovered John Butler. Things haven't been the same since. “We started doing shows when we were 15, just as an acoustic duo. But we were never really good at adding other people into the band, so one thing led to another and it's just evolved – this is where it naturally went.”