We were already sweating when we started to dig, and soon we were positively pouring. The ground was neither clay nor rock but something in between – a hard, shaly, grey-brown compound that sometimes broke away in lumps and sometimes split up into flakes with sharp edges. To save batteries we worked with minimum light, using only one torch at a time, whacking our short-handled picks into the face, levering out whatever the blades had got hold of, and shovelling loose spoil away with our hands. From past experience I already knew that Pav stank like a badger when he got hot – Pavagrotti, he was sometimes called – and now, at close quarters and in the confines of the tunnel, he was overpowering. But I realised I was smelling probably as bad to him, and said nothing.

Toad, as always, worked in silence, but after twenty minutes or so he stood up and said, ‘This one’s ready.’

Out of its cover, the SCR reminded me of the head of a robot, with twin aluminium antennae, linked by a cross bar near the base and rigged on the top like a pair of miniature rugby goal posts. I knew that Toad wanted it installed as high up the ventilation shaft as we could get it, and we’d worked out a means of fixing it in position. From behind our block at Balashika we’d scavenged three pieces of angle-iron and had cut them into twenty-four-inch lengths so that they’d jam across the shaft at an angle beneath it, and lock in position when its weight came down on them.

Standing with my head up the duct, I chopped at the brickwork above me with hammer and chisel to make three notches that would take the lower ends of the struts. Chips of brick kept flying into my eyes, but the grooves didn’t need to be very deep, and after one trial with a length of angle-iron, to make sure it would seat itself properly, we were ready to lift the SCR into place.

As a temporary support, we’d brought an aluminium pole made of short sections that slotted into one another. It was part of another satellite aerial system, and we’d worked out that we could stand it upright, with a circular pad on top, to take the receiver’s weight between lifts.

When Pavarotti and I raised the box to waist height, Toad slipped the first section of pole in vertically beneath it.

‘OK,’ he said, ‘rest there.’

Another lift, to chest height, and he got another section in.

The pole, longer now, started to wobble and flex as it took the weight. ‘Keep it steady,’ said Toad.

A third section propped the receiver at head height. The final hoist, into the shaft, could only be done by one person, pushing up with both arms above his head. I delegated the job to Pavarotti, as he’s taller and stronger than me.