It was a balmy November night in Seville and, amidst the glitzy bedlam of the MTV Europe Music Awards 2019, Mabel McVey was locked inside her dressing room.

She’d just nailed the biggest performance of her life, and her route off stage was punctuated by screaming encouragement from her team, but she couldn’t rest until she’d seen it for herself. She made a beeline for her manager Radha Medar to check she’d filmed it and, as soon as she heard ...