Ben must have been expecting the question, but still he hesitated before answering. ‘It was the anniversary of the Braer disaster. You know, the tanker that went aground at Quendale, leaving a slick of oil miles wide?’

Perez nodded. The disaster had made national news for weeks. Shetlanders had made a fortune out of the visiting media.

‘Nothing had changed! I mean, still people don’t take environmental issues seriously. I broke into the terminal at Sullom Voe.’

‘And did thousands of pounds’ worth of damage to oil company property.’ Perez had been working in the south at the time, but the Shetland police had still been talking about it when he joined the service there.

‘How much damage did they do to Shetland wildlife?’ Ben sat back in his chair, not really expecting an answer. ‘My mother came to court. She’d never been so proud of me.’ Perez couldn’t tell what he made of that. Would he have preferred a more conventional mother?

Perez slid Ben’s written statement across the table.

‘Is there anything you’d like to add to this?’ Perez asked.

‘I don’t know what you mean.’

‘I think you were close to Angela. She was more than just your boss, wasn’t she? Yet you don’t mention that in the statement.’ For a moment Ben just stared at Perez and it seemed he would maintain the poise, the pretence at confidence. Then he seemed to lose control of the muscles in his face. It crumpled. He screwed up his mouth and frowned like a child trying not to cry. Perez went on. ‘Why don’t you tell me about it?’

‘I can’t stop thinking about it,’ Ben said. ‘Finding her in the bird room. At first I thought she’d fallen asleep there. She worked so hard that sometimes that happened. I’d go into the bird room before starting the morning trap round and find her still in front of the computer. I haven’t been able to sleep since she died.’

‘That isn’t quite what I asked you.’ But Perez saw now that Ben would talk to him. The strain had come through pretending he didn’t care too much what had happened to the woman. ‘Tell me about your relationship with Angela.’

‘I worshipped her.’

And suddenly Perez saw himself as a schoolboy, intense and passionate, following his German student around the island, declaring his devotion. ‘What did Angela make of that?’

‘I expect she thought I was pathetic, ridiculous, but I didn’t care.’

‘Did she say you were pathetic?’

‘No, she called me sweet.’ Ben spat out the word.

‘You had sex with her?’

Ben flushed suddenly and dramatically. ‘Yes!’ Then, forcing himself to be honest: ‘Though not so often recently.’

‘She had sex with other men in the field centre too. And not just in the centre. Visitors, islanders even.’

The assistant warden didn’t answer.

‘How did that make you feel?’