Reluctantly Jamie removed his T-shirt and tied it round his face like a mask then tentatively climbed onto the roof. He shuffled towards the six-inch hole, trying to keep his balance as the roof began to wobble, and peered down into the pitch-dark water.

‘Nah, there’s nothing,’ Jamie quickly decided, desperate to get back to dry land or at least into the rowboat. But Mark wasn’t prepared to give up that easily.

‘Push it with your foot and make the hole bigger,’ he said. Above them, the crows circled and cawed angrily.

Jamie pushed his toe into the hole, trying vainly not to get his trainers wet. Egged on by his brother, he began stamping down as hard as he dared on the ripped edge of the horsebox. Finally, it gave way by another inch or two, sending a bubble of old, trapped air up into Jamie’s face. The stench was so rancid, that Jamie immediately bent over and puked into the lake, while his foot slipped through the hole filling his trainer with filthy water.

Mark started laughing, But Jamie did not see the funny side. ‘I only just got these trainers for my birthday! I’m coming back . . . this is stupid!’

‘You’re wet now,’ Mark giggled. ‘Stamp on it, go on. Make the hole big enough to see inside. Go on, Jamie! Don’t be a baby!’ Mark knew exactly what to say to rile his younger brother.

Jamie angrily started jumping up and down on the roof of the horsebox, splashing Mark in the process. They were both soaked now, but it didn’t matter – despite the horrible smell, they were having fun.

With each jump, Jamie brought his knees up to his chest, getting as much height as he could. And each time he landed, the hole opened up a little more. Until, with one jump too many, the roof finally split completely and gave way beneath his weight.

To Mark’s horror, Jamie disappeared beneath the surface and into the submerged horsebox.

The next five seconds seemed to last forever. Not knowing what else to do, Mark held his breath, as though he too was underwater. Finally, Jamie bobbed back up, gasping and slapping the surface of the water with his palms. He snatched at the air, trying to find the oar being waved above his head until Mark managed to guide it into his hands, pulling his little brother to the wall of the horsebox. Jamie draped his armpits over the top of the wall, wiped his face and gradually let the wonderful realisation that he wasn’t going to die sink in.