Guided by the beam from Charlie's Maglite, I positioned the pyramid so the hole was directly over his nail mark, and held it there while he put a battery-powered screwdriver to the first lug. Very slowly, very deliberately, the shaft of the screwdriver rotated. It took the best part of two minutes to screw it in tight. By the time the first three were in, my hands were almost numb.

A different voice shouted from inside. It was closer, but it wasn't talking about us. He was complaining about the rabbit noise, and I couldn't blame him.

The sweat on my back was starting to cool and I could feel fingers of wind fighting their way down my neck. At last, Charlie fixed the last lug and I gave the structure a wiggle left and right to test it was stable. He was the mechanic; I was the oily rag. The rest was up to him now.

He retrieved a drill bit half a metre long and seven millimetres in diameter from his day sack and threaded it carefully into the pyramid hole, oblivious to everything else that was going on.

He blew on his fingers to warm them, then eased the drill in further until it just touched the wood of the exterior wall. This kit couldn't be worked by any old knuckle-dragger, which ruled me out. It called for a delicate touch and a steady hand. Charlie was the best of the best; he always said that if he hadn't gone into this line of work, he'd have taken up brain surgery. Maybe he wasn't joking; I saw him settle a bet once by turning one five-pound note into two with a razor blade. Back in Hereford, they called him the CEO of MOE [method of entry]. There wasn't a security system in existence that he couldn't defeat. And if there was, he wouldn't lose any sleep over it. He'd get me to blow it up instead.