IT’S simply a matter of time before commercial Australian radio starts playing Brit pop rock band The 1975. That’s the theory of frontman Matthew Healy, who is in Australia for his second time this year touring with the band, thanks to overwhelming online support. The group play Sydney’s Metro Theatre tonight and sold out the 2000-plus venue in less than 10 minutes. “Like anything, they will catch up. There’s a massive demand for the band and its young kids on the internet,’’ Healy said.