‘Some men I met.’

‘Why would they give you money?’

‘They saw me winning, and staked me to play for them. I have a system, Mottl, based on simple probability theory. I’ll explain it to you some time. Anyway, it seems to work. I keep half my winnings and give the rest to the syndicate.’

‘No system is infallible.’

‘Try mine,’ said Dovidl, rigid with conviction.

His method, so far as I could grasp it, was based on exploiting the freedom of the individual against institutional rules. At blackjack the croupier always wins a tied hand. But the player, said Dovidl, has a much greater advantage. He knows exactly what the dealer is going to do, because the dealer is bound by house rules. ‘I know his constraints,’ said Dovidl, ‘but he has no idea how I am going to play. It’s the same as a cadenza in a concerto. The conductor and orchestra follow the composer’s score right the way through but I, the soloist, can do as I please when we reach the cadenza of each movement. They cannot anticipate, all they can do is wait for me to let them back into the game.’

‘How does that work at cards?’

‘If the dealer draws anything from thirteen to fifteen, he has to take another card. This, in all probability, will bust him, since there are twenty cards worth nine or more in a pack of fifty-two. It’s madness to twist on thirteen, but under the rules he must do it. I, on thirteen, have a choice to stick or twist. Mostly I will stick and bluff. Sometimes, to confuse the dealer, I will take another card. Three games out of five, on average, I win.’

‘And roulette?’

‘There is no point in betting on reds and blacks. Fifty-fifty is a fool’s bet. I play a spread of five numbers, with in-built aleatory variants.’

‘Meaning?’

‘Three of the numbers are fixed for the night, the others can vary within a limited range. The combination of fixity and flexibility obscures the mathematical method, making the croupier think I am just another chancer.’

‘And it works?’

‘More nights than not.’

‘And if it fails?’ I persisted.

‘It can’t fail,’ said Dovidl coldly.

A shutter slammed down, walling me off from his confidence. Sensing my awareness of the barrier, he rushed to reassure me. ‘Don’t be such a worry-guts,’ grinned Dovidl, pinching my close-shaven cheek. ‘I’m not playing for big money. I’m not a compulsive gambler and I am not getting into anything that I can’t control.’

‘So why bother?’

He stopped the driver on Abbey Road, telling him to keep the change from a ten-shilling note. We walked the last hundred yards home, talking ruminatively in low voices.

‘I like the money,’ rumbled Dovidl, as we turned into somnolent Blenheim Terrace. ‘The money and the kicks. You must have felt it – the high you get when the wheel spins and a hundred quid hangs on the fall of a ball.’