has been trying to make the best of it. She settled down with the treat of the new Norman Collins, and for a while this worked perfectly well, but then finds herself instead thinking of waterfalls, or more particularly of one waterfall, the one up in the woods behind the house in Scotland, and the sound it makes when it’s in spate in spring, melt water churned to milky coffee, the sound that you can hear from all the back rooms of the house, that rushes at you when you open a window and let it in, along with the sweet wet air. Her own skylight is propped open to let the London afternoon swirl through, all smuts and dust and diesel fumes. She can hear traffic going past at the top of the street – the occasional motor car or van, the clop of horses and creaking drays and carts, and she can hear children playing and music from someone’s wireless and she feels pretty much content. This is not so bad, after all. She can manage. But she can also hear a waterfall, and there are no waterfalls round here.

She puts the book aside, and goes to the front casement and peers out into Woodland Road. It takes a moment for her to work out what’s different. The little grocers on the corner is shut, the blinds drawn. Mr Pritchard two doors down is on his knees in his small front garden, and Ilse and Hedy are playing hopscotch on the pavement, and Mrs Suttle is lugging a bulging string bag down the street. And all of that is perfectly ordinary. But Mr Pritchard’s trowel is forgotten in his hand, and he is twisted round to look up at the sky. And Mrs Suttle has stalled in her tracks, her mouth open. And Ilse and Hedy, who live with their aunt Miss Beck just down the road, are frozen at the hopscotchgrid, Hedy stopped on a square, Ilse holding her pebble as she waits her turn. They are all looking up, over the tops of the houses, into the distance. Charlotte cranes round but can’t see what they’re seeing. She leaves the casement, climbs onto the bed and heaves the skylight wide. Head and shoulders out among the slates and chimney pots, she startles a pigeon; it stares at her with an eye the colour of fire, then flaps away. The waterfall is louder here. A swarm of insects hazes the eastern sky with grey. A dark central core; around it there’s a shimmer of continual silvery movement. For a moment she can’t make any sense of it, doesn’t know what this that she is seeing.
And then she knows.

She drops back into her room. She slams the window shut. And then a siren starts up, the sound catching under her ribs, and squeezing her lungs. So this, after all, is it. You have to stay calm, don’t you; it’s important to stay calm. She grabs her cardigan, her coat, her bag – rummages through identity card, purse, keys, ration book, lipstick, toothbrush – her gas-mask in its cardboard box, and her Norman Collins. All of this juggled and slipping, she fumbles her door shut and races down the stairs. On the landing below Mr Gibbons is pulling on his greatcoat, steel helmet dangling on its strap over his arm.

‘Oh my word,’ she says.

He nods…