When you're depressed you retreat and you go into a smaller world. This is why Brighton worked well for the story, because it's a smaller world than London.

Lately Mirabelle had reflected wistfully if people even noticed her – a smartly dressed woman who came and went along the Promenade, always alone.

When she first moved to Brighton, the flat on the Lawns had felt luxurious and it had seemed as if she was settling down, sleeping in the same bed every night, the darkness uninterrupted by any hint of emergency. It had felt as if all her difficulties were over.