Seeing Rick frown, he added in a patronising voice, ‘I wouldn’t worry about it. You can take it from me that it’ll be OK. I could go into a more technical explanation, but I don’t think you’d understand. The bottom line is that the satellite sends signals down, and the SCR only answers for a split-second every twenty-four hours.’

He looked round the row of faces, clearly enjoying his role of teacher. ‘For security when the devices are being moved around,’ he went on, ‘there’s this very useful piece of equipment.’

He crossed to the end of the small case marked A-R and applied his thumb to a shallow depression near one corner. The sprung lid of a small compartment flew open, and from it he took out an object the size of a compact mobile phone. ‘This is the radio alarm trigger, generally known as the Rat. Whenever this is switched on it has to remain within thirty metres of the device. If it goes farther away than that it automatically triggers a radio alarm in the device itself. The signal can be picked up by satellite. So if you have to move the device in enemy territory, I suggest that the guy in charge keeps the Rat on his belt – like this.’

He clipped the thing on to his own belt, then returned it to its lair.

‘What about having a shufti inside one of the components?’ I suggested.

‘Not a chance.’ Toad started dry-washing his hands again. ‘They’re all sealed down, and I don’t want to break them out until they’re about to be put in position. There are quite a few checks I’ll have to make then.’

We couldn’t argue with him and he knew it. He wouldn’t even come clean about the damage each bomb was likely to do. He pretended the information was classified and kept it to himself. We had to be content with staring at diagrams of bewildering complexity which he brought up on a lap-top from his own CD. We all knew, though, that the destructive capacity packed into the black boxes in front of us was something awesome.

‘What would happen if we got the devices in position but didn’t prime them properly?’ I asked. ‘What if you deliberately connected them up wrong?’

‘The satellite would detect the fault. That’s the beauty of the system. The Pentagon would know there was something wrong. They’d probably send us back to put it right.’

‘Well,’ said Pavarotti, as if to sum up. ‘I’m not going down any fucking tunnel. That’s for certain.’

‘I wouldn’t be so sure,’ I told him.