She is the home-schooled 17-year-old pop superstar. Billie Eilish tells Decca Aitkenhead how success has altered her life — for better and for worse.

When teenagers dream of becoming pop stars, I imagine the scene they picture is pretty much this: a matte-black Dodge Challenger pulls up for a photo shoot in a fashionably obscure Los Angeles neighbourhood. A documentary film crew is poised at the studio door to capture its arrival. Inside, a dozen or so creatives wearing baseball caps and black arrange vegan snacks among the vintage vinyl and French fashion magazines; racks of jewellery and rails of