Pim admitted to Claire the other morning that he was ‘gobsmacked’ that Ash had got so involved so quickly, but she can tell that he’s impressed.

There are people – mostly women of a similar age to her – walking from all directions to the beach, like iron filings drawn to a magnet. As Claire gets to the pebbles, it really does feel as if she’s joining a flock. Usually their Sea-Gals gang gather alone by the groyne, but this evening there are little groups of swimmers strewn out across the pebbles, greeting each new arrival with a hug. The sky is dappled with a full array of fading pink, purple and grey hues as night approaches. She’s so used to this bit of beach, but the atmosphere feels more charged. There’s a sense of occasion, but it’s the deep purple of the sea that feels the most different. It’s alluring, like seeing a friend you’re used to seeing in tracky bottoms dressed up for a night out.

Dominica and Tor are already on the beach, changing. Maddy has sent her apologies, but she’s not going to make it, and Helga is late, which is unusual.

As they change, they discuss the tide.

‘What does peregrine mean?’ Claire asks. She’d told the boys that she was swimming at the peregrine tide, quoting the WhatsApp message as if she knew what she was talking about.

‘It’s the point where the moon is closest to the earth in its orbit, so if we see it, it should look big,’ Dominica says.

‘Low tide was at six,’ Tor says, ‘so it’s coming in. It looks just right.’

Around them, the swimmers are collectively stripping off, their Dryrobes falling to the beach, the hats and boots and gloves going on next, and then there’s a whole mass of bare thighs and arms. Dozens of women of all shapes and sizes, and a few men too, approach the water, tiptoeing across the stones.

Claire smiles as she hears the screams of delight as the swimmers get in the water and she remembers reading that someone had described the collective noise as ‘sea opera’. There’s certainly something grand and musical about the sound as the crowd bounce around in the bobbing waves. There’s a collective whoop as a big wave breaks over their heads.

‘You coming?’ Dominica asks, noticing that Tor is lingering, but she’s looking at her phone. ‘I’ll wait for Lotte and the others,’ Tor says. ‘You go.’

‘Keep an eye out for Helga, too. It’s not like her to be late,’ Dominica says. ‘Come on then, Claire. Let’s do this thing.’

It’s not as cold as Claire has been anticipating and, with so many swimmers in, it feels like a party in the sea, as if everyone is dancing around each other in a disco. To her surprise, Claire recognises quite a few of the faces among the swimmers. There’s the owner of the café, who smiles and says hello, the lady who works in the physiotherapy department at the hospital who helped sort out her knee years ago. She’s wearing a jaunty retro swimming cap with purple flowers on it and Claire wonders again where Helga is. She’d love this.