Tea-stalls and greasy cafés formed pinpricks of light on a periphery of shadow. Short men with sharp features flickered in and out of sight. Restaurants heaved the drunk and merry into the maws of growling cabs. The completely incapable were turfed into the gutter, squatting on the kerbstone where they took up the tuneless ditty they had been trying to sing when the pubs shut. Small pools of vomit decorated the pavement, among cabbage leaves and spent bus-tickets. Powdered old women – prostitutes off the Piccadilly meat-rack, Dovidl whispered – hung around for one last trick of trade, or a free gift of bruised fruit. A cycling policeman purred through pedestrian alleys, to cries of ‘Wotcher, Bill, fancy a bit?’ The market heaved with wooden crates and ageless ribaldry. I was smitten by the sights and smells, but Dovidl had more pressing matters in mind.

He led me past Bow Street police station along an alley and down a flight of steps to a heavy basement door that yielded at his triple knock. I could barely see inside, so thick was the smoke. When my eyes stopped watering, I found myself in something I had read about in the novels of Patrick Hamilton and Graham Greene but never expected to visit: an illegal gaming club, a den of vice and squalor.

Dovidl seemed to feel at home. He pecked the hat-check girl – on the lips, I noticed – ordered a glass of champagne ‘and a lemonade for my teetotal friend’ and exchanged a wad of five-pound notes for chips of many colours. Where had he come by so much money?

He strode to a green-baize table and sat down, signalling to the unoccupied croupier to deal him two cards.

‘Will your young friend be playing, Mr David?’ said the dealer.

‘Not so young, Tony,’ said Dovidl. ‘He’s here to learn.’

They played a game I knew from the sixth-form common room as pontoon. Here it was called ‘blackjack’. The object was to score twenty-one, ideally in two cards – royal or ten, plus ace – or, if your cards were poor, to bluff your opponent into thinking that you had a better hand, forcing him to ‘twist’ (take another card) and ‘bust’ (surpass twenty-one). I considered it a mug’s game. If dealer and player had the same total – say, nineteen – the dealer was deemed to have won. The game was stacked in favour of the man with the deck. Why bother to play?

Dovidl, however, seemed to be winning. His pile of chips mounted so fast that I neatly stacked a second pile, then a third.

‘Loaded, your chum is,’ said a posh-accented man on my right, squiffy with drink.

‘Talented, too,’ I replied.

‘Come on,’ said Dovidl, flipping a large green chip to the dealer. ‘I’m bored with this. Let’s move on to big game.’