Will shook his head. “But that’s where you’re wrong. People have died there. Seen things. And if 67you stay, then something will happen to you too—”

Charlie had looked more fascinated than unnerved up until this point, so I was surprised when he suddenly started to cry – and not just a bit of a sniffle but actual sobbing.

“I don’t want to stay in the lighthouse!” he wailed. “I hate it there – I hate it!”

I rolled my eyes at Will. “Thanks a lot,” I said. “I’m sure my dad will be really impressed when we take him home like this.”

Will shrugged and didn’t even try to apologize. He was clearly a bit of an arsehole.

I went to crouch in front of my brother. “It’s all right, Charlie. Will was only joking. The lighthouse isn’t really haunted. Come on, let’s go and see the rest of the island.”

To my relief, Will didn’t try to stop or follow us, and we left him standing alone on the path. Charlie continued to cry and sniffle for a bit, but then Rosie got him on to the subject of snails and he seemed to calm down and eventually forget about the unpleasant conversation with Will.

Once Charlie had settled, we carried on exploring the island. It wasn’t large. I guess you’d walk across 68it in an hour or so. Which meant that you couldn’t go far before you found evidence of the other guga hunters. We saw the bothies perched on the hillside first – the little stone houses built all those years ago by the monks. I had to admit they made the lighthouse look almost homely by comparison. The dark stone huts didn’t even have any doors or windows, only gaping holes in the rock for the wind to whistle through. There were several people in windbreakers busying themselves carrying bags back and forth and dragging great lengths of rope.

“Come on,” I said at last. “Let’s go on before they see us.”

We spotted a couple of baby gannets in their nests as we walked, and the thought of their fluffy white heads being bashed open on the rocks made me feel ill. I was glad that Dad’s research might help end the hunt. We explored a little more, but there was nothing on the island except birds and flies and the tall stone cairns. It was massively depressing. Finally we looped round to make our way back. Along the way, we noticed several other types of birds among the gannets, and Charlie could name every one.

“That’s a guillemot,” he said, pointing. “That’s a 69shag. The one by the big rock is a razorbill. And the one back there is a fulmar.”

“Oh, look, and there’s a snail.”

I pointed it out, but to my surprise he said, “Yuck, I hate snails! They’re all slimy!”