Singh sat forward and looked at each of the students for a moment. ‘I’d like you to think back before the trip. Had there been any problems between Leon and Mr Wilkinson?’

Oh, come on, you don’t think Leon killed him? Bradley replied, immediately animated and ready to defend his friend. He could never do something like that!

‘We’re not assuming anything,’ Singh replied, holding up a hand to try and calm Bradley. ‘We need to cover everything, that’s all.’

No, they got on really well, Bradley replied, then sat back and folded his arms, showing his refusal to engage with the question any further.

Kian looked nervous, but he nodded. I don’t know Leon as well as Bradley, but I don’t think he ever said anything bad about Mr Wilkinson.

The two girls nodded their agreement with Kian.

‘Okay,’ Singh said, changing tack. ‘Did Leon give any sign that he was upset or worried about anything on Friday?’

Bradley seemed to think for a moment, then looked over at Courtney. He seemed a bit preoccupied, like there was something on his mind, maybe. He was looking at his phone all the time on the bus and once we were in the cabin. Mr Wilkinson told him off a couple of times.

Forest took over. ‘Did he tell you why he was looking at his phone?’

Bradley shook his head. No, and I think he definitely wanted to keep it private.

‘Thank you. We’ll look into Leon’s messages and see if that helps us work out what happened,’ Forest assured the students. Far from relaxing them, however, I noticed a look of panic flit across the faces of Bradley and Courtney. Had the detectives noticed it too?

‘What happened to Mr Wilkinson?’ Courtney asked, a tremor in her voice.

‘I’m sorry, but we don’t know yet.’

‘Leon wouldn’t …’ Courtney began, but then she stopped herself and shook her head.

‘What were you going to say?’ Singh asked.

‘Leon wouldn’t run away,’ she replied, looking down at the table as she spoke. I didn’t think that was what she’d been intending to say at first, but she didn’t speak again.

The detectives stepped out of the room for a moment, had a quick discussion, then came back in and dismissed the students, with an appeal to speak to them if they thought of anything else. The four teenagers barely waited for me to finish signing this to them before they all got up and left the room together, arms folded or hands in pockets, as if they were deliberately avoiding communicating with each other until they were away from us.