One side of the hostel overlooked Waterloo station’s 22 platforms. Trains departed and arrived at the rate of two or three a minute. Another side abutted a Victorian cast-iron girder bridge over which suburban trains arrived and departed with rolling thunder, to which was added that fingernails-dragged-down-a-blackboard, pigs-screaming-at-feeding-time, metal-on-metal noise as the trains negotiated a bend whose curve was at the very limit of what was geometrically feasible for fixed, in-line bogies. On the remaining side of this discordant triangle was an arterial road hazy with diesel particulate through which heavy traffic accelerated and braked between traffic lights.

I arrived here mid-morning after a Spectator party wanting only to lie down and die. The young guy who checked me in was insane with friendliness. He led me upstairs to a dormitory and showed me top bunk U. He watched me climb with some difficulty up the metal frame until I had safely swung my leg over the top bar, then he wished me a pleasant day and departed. I lay gratefully on my back and listened to the volley and thunder of rail and road traffic coming in through the half-raised sash windows. The occupants of the other 21 bunks were elsewhere, indefatigably taking selfies next to famous London landmarks, I supposed. Then I fell asleep.

When I woke, there was a young man in the dormitory looking perplexed. Noticing my open eyes, he said, ‘Sir, do you know what the etiquette is for taking off one’s pants in a mixed hostel dormitory?’ The accent was Canadian, I guessed. I told him that as there were just the two of us present, and I was a hungover hack, he could take off his trousers with impunity.

Around six I abseiled down the outside of my bunk and went downstairs to the bar. The etiquette guy was standing at the bar looking perplexed. He recognised the cultural importance of trying a pint of English beer, he said, but he was at a loss to know which to try first. I ordered and paid for a pint of London Pride each and we carried them over to a comfortable sofa. ‘Cheers,’ he said, uncertainly. ‘The Queen,’ I said. Then he said, ‘Do we chink our glasses together now? Is that the custom?’ I recommended that we just steam into it, and gave a demonstration of what I meant.

His name was Nathan. Other information supplied, in descending order of importance, was that this was his first visit to England, that he hadn’t slept for 36 hours, and that he was a ‘political nerd’. ‘Oh yes?’ I said. ‘Yes, I’m a liberal.’ He had studied political science at university and represented his fellow liberal students at national committee level. So this Canadian liberal and I swapped views on nationalism, race, Trump and Brexit, while next to us three diminutive young Japanese women bent exquisitely over their pantechnicon suitcases, rearranging the contents.

Nathan was remarkably well informed about British and US politics. He expressed his opinions carefully and thoughtfully, and he could back them up with an extraordinarily wide range of facts, quotations and statistics. Not a single one of his opinions was coloured by either his emotions or his own sinfulness. There was no malice in him, or envy. Never in my life have I heard the case for the liberal imagination put so clearly or so matter-of-factly.

Obviously, I was talking to an alien robot, designed and programmed using algorithms based on back copies of the Economist. When I told him I was a populist and that I had voted for Brexit, for example, a deep-level search of his program was instigated, and his normal power supply was diverted to assist with this emergency. For a worrying hiatus of several seconds it appeared that his entire operating system had frozen. Then power was restored, the robot was reinvigorated, and the negative result of his deep search was revealed by the neutral emergency default verbal reply of: ‘Oh, really?’

I didn’t think I’d sleep well that night. Of 22 people asleep, I figured the starting price of two to three snorers was very short. In the event, however, the dormitory was remarkably peaceful. I didn’t see the person in the lower bunk turn in. I was already fast asleep when he came. But whenever he turned over in the night, our bunk lurched violently like one of those flight-test modules one sees at the fair. And no wonder. When the trains began to thunder at 5.30, and he stood up and went to the toilet, I saw that he was about six foot eight and must have weighed about 20 stone. ‘Top of the morning, chief,’ I said to him as he returned and looked down on me. But I don’t think he spoke any English.