At the end, before the bridge approach, Whinger pulled into the kerb and stopped in a dark area between street lamps.

‘Right, lads,’ I said. ‘Just to confirm. The time now is 2105. Drop-off will be in five minutes, at 2110, near enough. A couple of minutes to reach the stable. We’ll assume Toad can manage the locks in five minutes. If he has any trouble, Pav, you have a try. That means we should be in the tunnel by 2120 at the latest. Half an hour to suss it out. Back at the ladder by 2150. Pick-up at 2155 from this street, south side, east of the gateway. OK?’

Everyone nodded.

‘I don’t think the radios will work underground,’ I added, ‘but everyone stay on listening watch. Pav and I are One, Whinger Two, Toad Three. Our ERV is over there, under the bridge. Right, then – let’s go.’

Whinger swung round and drove back at a moderate pace. Now the gateway was on our side of the road. One car overtook at speed, and we watched its tail-lights draw rapidly away into the distance.

Whinger was slowing.

‘Nothing behind,’ I said. ‘Now!’

In seconds the three of us were out and under the gateway. I heard, rather than saw Whinger pull away behind us.

I led us forward into the dark courtyard, keeping to the right-hand wall. Above our heads, lights were showing in a couple of windows; straight ahead the little church sat hunched in shadows, jutting from the left wall of the yard, and the inner road swung past its entrance at the right-hand end into a second yard at the back.

From an intensive study of the plans I had every inch of the layout in my head. Five metres past the door of the church we’d come to the end of the building on our right. Beyond it, set back farther to our right, was a run of smaller structures – old stables. The second little building from our end would be open-fronted, or at least without a door. The head of the shaft was in the back of that shed, behind a wooden partition.

Moving quickly, we came level with the door of the church, which stood slightly open with slivers of light shining through top and bottom. Women were talking inside, their voices rising and falling. We reached the corner of the tall building. There, just visible in the gloom, stood the low range, a few metres farther on. A dozen quick steps brought us to an open doorway.