‘All the years that I’ve been staying at Harbour Street I only once had a real conversation with Margaret. She had a flat upstairs and rarely came into the visitors’ areas except for work. But one evening we came into the house together. She’d crossed the road from the church, I think, and I was chilled after a day on the water. I invited her to join me for a drink, and we sat together in that dark, gloomy lounge.’ He paused. ‘I probably talked about my work, my family. I’ve been married for forty years and have grandchildren of whom I’m ridiculously proud. Happy people can sound very smug, and I thought suddenly that she wasn’t happy at all. That the quiet efficiency was a show, and underneath there was a terrible desperation. I asked her about her husband. Did she ever see him? “Oh no,” she said. “He’s long gone.” Then she said something very odd. “Secrets are all I have left.” I didn’t ask her what she meant. I could see that she wouldn’t tell me.’

Holly made detailed notes. Some of it didn’t mean much to her, but Vera had been in the guest house and it would all mean more to her. She turned back to the professor. ‘You spent yesterday with Malcolm Kerr?’

‘Yes. He took me out to Coquet Island. My research is into water temperature and how small changes can have an impact on microorganisms and therefore affect things further up the food chain. We collected samples. It’s meticulous work – some might say tedious. It took until the middle of the afternoon.’

‘You don’t have a student to do the fieldwork for you?’ Holly had once gone out with someone doing a PhD, who was always complaining about doing the donkey work for his supervisor.

Craggs gave a little laugh. ‘I’m what you’d call a control freak. I like to be in charge of my own data.’ He continued to twist the ring on his finger. ‘Besides, I enjoy being on the water. That was what drew me to the subject in the first place. A passion for ecology and for open spaces. I’m due to retire next year. I’m not quite sure what I’ll do with myself. Write a book, perhaps, like all retired academics.’

‘You must know Malcolm Kerr well then?’