RDX fitted that bill perfectly. Its proper chemical name was cyclotrimethylene trinitramine but Britain’s Royal Arsenal, who had first developed the formula during World War II, had called it ‘Research Department Explosive’ and the acronym RDX had stuck. It had been used in the Dam Busters raid against Nazi Germany in 1943. In modern times it was still favoured as a component of military bombs, and also terrorist ones, due to its stability, plasticity and extreme potency, which was significantly greater than that of alternatives like TNT or dynamite. And it was safe. You could whack it all day long with a lump hammer, shoot holes in it or set it on fire. Nothing except a detonator or blasting cap could make it go bang. Civilian operators liked it for the same reason; hence, RDX was a primary ingredient of Semtex, used in commercial demolition and quarrying.

‘They must have used a truckload of the stuff when they built this place,’ Ben mused.

‘Wi’ just a wee bit left over after the job wiz done,’ Boonzie replied. ‘Should’ve been disposed of or kept under lock an’ key. Naughty, naughty. An’ now it’s gonnae bite them on the bum. Look.’

He motioned for Ben to peer inside the larger of the two cardboard boxes on the workbench. Ben looked, and knew what he was seeing. Boonzie had used half of the RDX and all but one of the detonators to rig up an arsenal of twenty small but powerful one-pound bombs. Each device had a yellow number spray-painted onto it.

‘Check this oot.’ Boonzie showed Ben something that looked like a walkie-talkie. It was a radio remote detonator trigger device with multiple channels allowing one bomb at a time to be exploded at the touch of a button, or all at once.

‘Handy toy,’ Ben said.

‘Aye, an’ that’s not all the stupid buggers left lyin’ aroond for the wrong folks tae find.’ Boonzie reached under the bench and pulled out a cable reel wrapped around with what looked like bright blue nylon rope.

‘Detonating cord,’ Ben said.

‘A hundred metres o’ the stuff.’ Then Boonzie told him how he’d planned on using it, along with the remaining twenty pounds of RDX. ‘What dae ye think?’

‘I think you’re the kind of evil genius that gives evil geniuses a bad name.’

Boonzie flashed a roguish smile. ‘Then let’s get this show on the road, laddie.’