Maisie Williams — part glorious elf, part teeny-tiny hobbit — is sitting on a balcony in north London wearing a pair of fruity Miu Miu sunglasses and an expression of reeling adolescent panic. These are the dying days of her teens. In fact, by the time you read this, the girl from Bristol who is one of the most famous children who has ever lived, known to a gazillion fans as the micro-assassin Arya Stark in Game of Thrones, will have finally turned the big 2-0. “I’m calling it twenteen,” she says, and I nod sagely. Added to her woes is the fact that, after six years of furious dragons and blood-splattered cleavages, GoT is rumbling towards the first of its final seasons later