The shops turned into homes, some built in pinky-grey Devon stone, some painted, others fronted with slate tiles, followed by cul-de-sacs of new housing. Magnolias were coming into flower; frilled white stars against branches so bare they looked stripped. It was already one o’clock; he had missed the midday collection. He would buy a snack to tide him over and then he would find the next post box. After waiting for a gap in the traffic, Harold crossed towards a petrol station, where the houses stopped and the fields took over.

A young girl at the till yawned. She wore a red tabard over a T-shirt and trousers, with a badge that said HAPPY TO HELP. Her hair hung in oily strips either side of her head so that her ears poked through, and her skin was pockmarked and pale, as if she had been kept inside for a long time. She didn’t know what he was talking about when he asked for light refreshments. She opened her mouth and it remained hanging ajar, so that he feared a change in the wind would leave her like that. “A snack?” he said. “Something to keep me going?”

Her eyes flickered. “Oh, you mean a burger.” She trudged to the fridge and showed him how to heat a BBQ Cheese Beast with fries in the microwave.

“Good lord,” said Harold, as they watched it revolve in its box behind the window. “I had no idea you could get a full meal from a garage.”

The girl fetched the burger from the microwave and offered sachets of ketchup and brown sauce. “Are you paying for fuel?” she asked, slowly wiping her hands. They were small as a child’s.

“No, no, I’m just passing. Walking actually.”

“Oh,” she said.

“I’m posting a letter to someone I knew once. I’m afraid she has cancer.” To his horror, he found that he paused before saying the word and lowered his voice. He also found he had made a small nugget shape with his fingers.

The girl nodded. “My aunt had cancer,” she said. “I mean, it’s everywhere.” She cast her eyes up and down the shop shelves, suggesting it was even to be found tucked behind the AA road maps and Turtle Wax polish. “You have to keep positive, though.”

Harold stopped eating his burger and mopped his mouth with a paper serviette. “Positive?”

“You have to believe. That’s what I think. It’s not about medicine and all that stuff. You have to believe a person can get better. There is so much in the human mind we don’t understand. But, you see, if you have faith, you can do anything.”

Harold gazed at the girl in awe. He didn’t know how it had happened, but she seemed to be standing in a pool of light, as if the sun had moved, and her hair and skin shone with luminous clarity. Maybe he was staring too hard, because she gave a shrug and chewed her lower lip. “Am I talking crap?”