'I learnt it from a man who shared my dug-out near Ypres,' he said.

The Unprincipled Affair of the Practical Joker - (A short story where Wimsey makes a blackmailer appear to have been cheating at cards.) Here's what happened in that dug-out.

The dug-out shook with each near-miss of the barrage of Jack Johnsons. In the candlelight pale faces turned downwards to avoid the shower of dirt that followed. Major Wimsey, Sergeant Bunter, and several company runners were taking what fragile shelter there was to be had in the tiny room carved out of the clay, an all-too-thin roof of boards and sandbags above.

Sergeant Bunter's gaze was fixed on the Major. From long experience of reading his company commander's moods, he could tell that Major Wimsey's nerves were stretched to the limit. Wimsey was an excellent officer, he thought, but inactivity was a problem for him. No one cooler in action, but waiting told heavily on the Major. Bunter knew what had to be done.

"Major Wimsey, Sir."

"Yes, Sergeant?"

"Might pass the time if we had some entertainment, Sir."

"Can't say I feel much like a sing-along, in the circs. Bally explosions would probably ruin our harmony. Way too much percussion out there," said Wimsey with feigned nonchalance.

"I was thinking of a different sort of performance, Sir. You might not guess it, but Private Higgins here is a sleight-of-hand artist. Quite well known in the music halls. Higgins, come over here to the Major."

"S'right Sir. I useter be a top act in the halls, afore the War. Presterdigertation. Pull rabbits outter hats, make yer watch disappear and reappear in yer girl's bag."

"Well, Higgins, I know this isn't the West End, but could you show us a few tricks?" Wimsey's voice showed new animation, Bunter noted.

Higgins reached into a tunic pocket, and drew out a deck of cards. Unlike most decks Wimsey had seen in the trenches, they were spotlessly clean and crisp, suggesting that they weren't used for games.

"Care to cut the deck, Sir? Look at the bottom card before yer put the deck back. Don't let me see it." Wimsey did so, and noted that the bottom card was the Ten of Hearts. Higgins passed his hand twice over the deck. "If yer'd be so obligin' as to shuffle the deck, Sir?"

Wimsey shuffled the deck three times, riffling the interleaved cards back into place with a skill that would have had a riverboat gambler green with envy.

Higgins reached over to the deck, cut it, and revealed the Ten of Hearts.

"By Jove! That's the card!" Wimsey exclaimed.

"Now, Sir, if you'd arrange the deck by suits, Deuce to Ace in each one?"

Again Higgins passed his hands over the deck.

"Now, Sir, would you lay them out on the table?"

Wimsey started putting the card out. "Wait a minute! Where's the bally Ace of Spades gone to!" He dealt more cards.

"Hell! All the Aces are missing!"

"Really, Sir? Are yer sure you haven't just mislaid them?" He tapped Wimsey's tunic breast pocket. "Yer pardon, Sir, but I think there's one of them in there now." And he reached in and extracted the Ace of Spades. The Ace of Hearts was found in Wimsey's boot-top, the Ace of Clubs in Sergeant Bunter's haversack, and the Ace of Diamonds in Wimsey's holster.

"Splendid, Higgins!" Wimsey cried. "Just how did you do that? I had my eyes on you the whole time!"

Higgins dropped his eyes. "Well Sir, secrets of the trade and all…"

A short and animated exchange took place between Sergeant Bunter and Private Higgins, with Higgins's expostulations cut short by a short, sharp reply from Bunter.

"Well, Sir, seein' 'ow hit's you."

And he showed Wimsey how the cards had been subtly trimmed, so that the Ten of Hearts had the slightest possible edge exposed when lined up with the rest of the deck, so that nine times out of ten the deck would be cut at that card. Then he demonstrated how to palm one or more cards, and found Wimsey an excellent pupil.

"You've the right hands for this, Sir – long fingers. Them aces was never where I found them. In my hand the 'ole time.