‘I didn’t have the right to feel anything,’ Ben said. He seemed to have composed himself. Perez thought he had been through the same argument in his head many times. ‘I didn’t own her, I couldn’t dictate how she behaved with other men.’

‘That’s very rational,’ Perez said.

‘I’m a scientist. I am rational.’

Perez wanted to laugh out loud. There was nothing rational in this infatuation.

‘When did it start?’

There was a beat of hesitation. ‘My first season. I couldn’t believe it. I’d never met anyone like her.’

‘You hadn’t met her before you started work at the field centre?’

Ben stared directly at him. ‘No. Where would I have met her?’

‘Is she the reason you keep coming back?’

‘No!’

‘Where did you get together? It must have been hard in the lighthouse, with other staff and visitors about.’

‘In the Pund. That was our place.’

Perez nodded. The Pund was a ruined croft house. Once it had been set up as a bothy for campers, with a loft bed. Aristocratic naturalists had stayed there before the war but it had fallen into disrepair and was no longer used. It would be a romantic place for an illicit meeting and he could see how the young man would love the excitement of hiding away there, the sun slanting through the gaps in the roof, the charge of expectation when he heard Angela approaching.

‘You do know she was sleeping with Hugh too?’ he said.

‘He dropped hints.’ Ben kept his voice unemotional. ‘There have been other visitors and Hugh was her type.’

‘You didn’t discuss it with him?’

‘Of course not! None of my business.’

Perez had a picture of life in the North Light in the week running up to Angela’s death. The wind and rain making people feel trapped inside the building. Angela manipulating events for her own amusement, playing the young men off against each other, fuelling Poppy’s resentment, suggesting that Jane wouldn’t be welcome to return to the isle the following year. And Maurice? How would he have reacted to the mounting tension, to Angela’s games? Would he have welcomed them as one way of relieving her boredom, of ensuring that she would stay married to him? Perez thought the situation must have been intolerable.

‘Do you know which of the islanders was her lover?’

‘No!’ Ben was shocked. ‘It wasn’t something we discussed. She would have hated me prying.’ He paused. ‘If I’d asked about anything like that, she would never have seen me again.’

‘Was Angela undertaking a particular study at the moment?’

‘She was writing up the summer seabird census. I don’t think there was anything else.’ Ben frowned. How was this relevant? He seemed almost to resent the conversation moving away from his affair with Angela. He longed for the opportunity to talk about her.

‘Anything involving the collection of feathers?’ Perez asked.