‘She picked me up the first night I was here.’ Hugh had a smile, wide and welcoming, but fixed; there was somehow, even when he was talking, a shadow behind the words. It gave Perez the sense that he would take nothing seriously. ‘I was last up in the common room. I’d been drinking all evening. I’d wanted to visit since I first heard about the Fair Isle field centre; it was so cool to be there finally. I felt like celebrating. And Angela wandered through from the flat and found me there. “Let me give you a tour of the island.” It was a clear, still night, just before the westerlies started. Cold. There was ice on the windscreen. Unusual so early in the year, apparently. She took me up to the west cliffs and pointed out the lights of Foula right in the distance.’

‘You had sex?’

‘Twice that night. Once in the back of the Land Rover, parked on the airstrip, and once in an empty room in the North Light when we got back. It was three in the morning when she left me.’ He paused, added with admiration: ‘She was up at dawn to do the trap round.’

‘And on other occasions?’

‘Not every night. She’d made it quite clear we met up on her terms. She’d come and find me when she wanted me.’ Hugh spoke without apparent resentment. He wasn’t like Perez with his first lover; it seemed Hugh had no interest in forming a permanent relationship. The smile remained in place.

They’d reached the peak of a ridge and now had a view north. The only sign of habitation from here was the lighthouse and that was almost obscured by a fold in the land; only the tower and the lens were visible. Perez remembered when the lighthouse was manned: there’d been a Glaswegian couple with a little boy who’d come to the island school, a bluff retired merchant seaman as senior keeper and they’d all lived in the whitewashed buildings at the foot of the tower. Then the field centre trust had taken it over, raised the money to convert it. From this position he became aware again of how isolated it was.

‘Did she come to find you?’ Perez asked.

‘Oh, yes. At odd times. Once in the middle of the day when everyone else was having lunch. We were in the dorm. Dougie could have come in at any time. But that was what she liked. The excitement. The danger.’

And you? Perez wanted to ask. Did you like it too?