‘I met her when she was an undergraduate,’ Berglund said. ‘A few years ago. That hot summer. She was volunteering on a dig I was managing in the south of England.’ He stopped speaking, stubborn, challenging Perez to ask more detailed questions.

‘Why didn’t you tell me you’d met her previously?’ Perez kept his voice pleasant. If the man felt threatened he might stop talking altogether.

‘It slipped my mind. I’ve worked with a lot of undergraduates over the years. Then when I did remember I didn’t want to make too big a deal of it. I thought you might misinterpret the incident, take it out of context.’

‘You took her out to dinner,’ Perez said. ‘One evening in that hot summer, you asked her to go out with you. Just her, not any of the others. Tell me about it.’

Berglund hesitated. Perez thought he was deciding how much he would have to give away. At last he started talking and it was almost as if he was telling a story.

‘She was a pretty little thing. I suppose she was still attractive when she was working in Whalsay, but here she could be so earnest. Back then she seemed happier, funny, full of life. Yes, I invited her out to dinner. A couple of times, actually. A spur-of-the-moment decision that I went on to regret. I was married and I had a small child. But after a long day in the field I wanted someone to share a beautiful evening with. I like female company and my wife was two hundred miles away. That was all.’

‘Did she know you were married?’

‘I didn’t tell her but it certainly wasn’t a secret. The other volunteers would have known.’

‘What happened?’

‘The first time, nothing. We shared a meal and I dropped her back at the site. The next time was more intimate. We had a meal in the pub where I was staying. The windows were open and there was honeysuckle in the garden. I remember the smell of it. We shared a bottle of white wine. Then we went to bed together, inspector. Not a crime. I wasn’t even her teacher and she was a consenting adult.’

‘She was young and very naïve.’ Not a judgement, a comment. Perez wished now he’d asked for a drink. His hands were on the table in front of him and he didn’t know what to do with them.

‘As you say she was young and naïve. She read more into the encounter than I’d expected. Most students are more sexually experienced than I am. She was an exception.’ He paused. ‘She was nineteen, I was thirty-five. She fancied herself in love with me.’

‘Did she make life difficult for you?’