We walked on, until we became aware of a handsome, old-style building set back from the road behind a courtyard on our left, and flanked by two matching outliers, evidently part of the complex. Beside the gate, in a grey pillbox, were two Russian guards in uniform, chatting, smoking, looking bored and not paying attention. Behind them, further in, was a stone gatehouse containing a guy in a red jumper who sat at a desk behind a glass screen.

‘Bet that’s a Brit,’ I said. ‘He’s a bit more alert. He’ll be controlling the electronic gates and the phones.’

‘Look on the roof,’ said Rick, ‘left-hand corner. There’s an infra-red light. They must have good security systems.’

We crossed the street towards the gates, where a brass plaque announced that the building was the British Embassy. The discovery made me feel a little better: at least we’d carried out one small but useful research task.

We recrossed the river by the next bridge, watching our rear all the way, and returned to base along the north side of the Kremlin, past the Tomb of the Unknown Soldier, where a perpetual gas flame burned out of a horizontal slab, and a cloak made of bronze lay folded over a plinth. We paid our respects and walked on.

Then, only a minute or two away from the hotel, we were nearly caught up in a violent incident. Fifty yards ahead, facing us, a single car was parked against the kerb. Suddenly a grey van hurtled past us from behind. Tyres screeched as it scorched to a halt inches in front of the car, blocking any take-off. From the van burst four figures in uniform – militiamen, by the look of them. They ran at the car, ripped the doors open and dragged out the driver and passengers.

In seconds the three guys from the car were spread-eagled over their own vehicle, taking heavy punishment from batons. Then one of the uniformed men stood back in the road and fired a couple of short bursts from his sub-machine gun, aiming into the air over the river. His purpose seemed to be to scare the shit out of the targets – and I wondered where the bullets were landing in this huge city. As if to emphasise what he thought of his victims, another militiaman ran in and swung his boot, delivering a fierce kick to one of the huddled bodies, catching the man in the small of the back, whereupon he sank to the ground with a groan.