He hadn’t thought to tell her where he was. He’d completely forgotten. Christ, what was wrong with him? What if she went back home and – he scrabbled in his pocket for his phone.

“Got to text my daughter,” he explained to Steve, stabbing frantically at the buttons.

Alicia pet, had to go out for an hour. Pub is locked. Have you got your key? Love Dad xxxxx

Sometimes it took her hours to reply, but this time she answered instantly.

No probs Dad tx for letting me no Axxxx

Where are you? xxxxx

Again her reply was almost instant.

Just out with friends like I said remember!!!

Love you loads see you l8er xxxx

Yes, but which friends? He’d thought she was down at the beach hut. That mystery boy, no name, no face, just a collection of acts and sensations. Keep her safe. Let her go. Competing impulses, wrestling for supremacy. He put his phone away and strode on. He could hear Steve breathing hard as he tried to keep up.

“Just round here,” said Donald, in the faintly accusing tone of one pointing out the obvious. “It’s just… ”

The place where the beach hut had stood was empty. In this grassless landscape there was no yellow faded patch to mark its vanishing, no flattened plants springing sturdily back to life. Not a scrap of rubbish; no indentation where the gas bottle had rested. It was as if they’d only been there in his dreams.

Loss coiled painfully in his belly. He told himself it was simply because he’d imagined a triumphant confrontation.

“Looks like they’ve moved on by themselves,” said Steve.

“Not a chance,” said Donald.

“This is definitely where they were?”

“Oh yes. This is the place. But they haven’t gone. They said they’d be here until midwinter.”

“We do find travellers’ plans can be quite fluid,” said Steve. “They may have decided on the spur of the moment.”

“Not a chance,” Donald repeated. “They’ll be back. I know it.”

“Well, I can’t really complete a welfare assessment if they’re not here for me to assess them,” said Steve. “And since they seem to have gone, it looks like we can close off the case.” He looked round at the smooth gold curves of the dunes. The topmost dusting of sand riffled in the breeze. “They’ve left it very clean.”

“They’ll be back,” said Donald stubbornly. When Steve glanced at him, Donald saw in his eyes the faint suspicion that these beach hut dwellers had never existed. “If you come again tomorrow, you’ll find they’re right back where they were.”

“Thanks for showing me, anyway,” said Steve. “To be honest, it’s always better when these things resolve themselves. But if you have any more trouble, with them or anyone else, give us a call and we’ll start again. Okay?”

Donald heard the unspoken message: This is now over. He watched Steve walking away. A stout black Labrador pranced heavily towards him, and Steve pulled its ears in a friendly manner. Perhaps he and the girl who’d phoned him would laugh. Perhaps Steve was the fiancé. The Labrador’s owner called a sharp syllable and the dog nosed greedily in her hand. How had they got the beach hut down so fast and left so little trace? A butterfly, out of season and improbably blue, fluttered around Donald’s ear, then settled on his shoulder. Looking more closely, he saw it was a large flake of blue paint.