Before I describe how Irene and I made a wager that ended with my being seduced on a tiger skin in the Tankerville Club, I'd better explain why I want to tell this story here. It takes me back to the early eighties.

I've told you that I left Mycroft because I was jealous of Lady Bartlett. Having learned from her that there was nothing to be jealous about, I've taken her advice and I'm letting Mycroft stew for a while before returning to him.

Living on my own in Norfolk at present, I've passed the time in writing down the adventure of the Royal Revelations. Now I've decided to write about my early years, how I began masquerading as a man in the Diogenes Club, and what part was played by that fatal gemstone, the Flame of Natal.

You may remember that in the adventure of the Royal Revelations I stayed well in the background when the Prince of Wales called at the Diogenes. It wasn't because I was overawed by royalty. The truth was that I was terrified in case he recognised me.

I still can't explain how he didn't, for if anyone has an eye for a pretty face it's Bertie, as he likes his lady friends to call him, and, as I've admitted in The Royal Revelations, I was one of his lady friends for a while.

I hope I'm not boasting, by the way, if I suggest that I'm reasonably attractive. Also, I hope that you don't think I'm promiscuous with men, because I am certainly not. I know I'm living in sin with Mycroft, but he's only my second lover, after the Prince. And becoming the mistress of the Prince was a kind of accident, as I shall explain.

As I've said elsewhere, I once lived in America with an aunt, but I longed to return to England and go on stage. In 1882, at the age of eighteen, with five pounds in my pocket, I came back to London to earn a living.

The Royal Court Theatre took me on, and for a year I shared rooms with Irene Adler, who was coaching me in voice and singing. She always brushed aside my promises to pay, saying she'd do it for nothing, but I felt guilty and wanted to give her something. I knew that she was as short of cash as I was.

Irene had already appeared at La Scala, and was shortly to become prima donna at Warsaw. She wasn't yet well known in London and was as fond of spending money as she was of making it. The trouble was, like me, she never had any.

Because she was from America the London managers thought her just a little too brash for their tastes and she found herself struggling for a while. She became friendly with me when she discovered that I had lived some years in Ohio and the West. I had acquired something of the American drawl and at first she thought I was a countrywoman of hers.

One September evening in 1883 Irene persuaded Arthur Pinero and W S Gilbert to take us for a meal, since I'd just had my nineteenth birthday. The conversation turned to discussing why women could not go where they pleased, such as restaurants or theatres, without having to depend on men to take them out.

"I can go where I please whenever I wish - alone," said Irene. She was a little tipsy on the champagne.

"Get away with you!" said Gilbert with a disbelieving smile.

"I often do," she continued. "I have a gentleman's evening dress suit, and I sometimes go walking out in it after dark."

She had a lovely voice, a silky contralto that she brought into full effect when she wanted to impress the men in her company. It worked on Pinero. He quivered ever so slightly and his eyes opened wide.

"Really? And where do you go?"

"Not far. I'm not too daring. I stroll round Piccadilly."

"With a poppy or a lily in your mediaeval hand!" we sang in chorus, to Gilbert's great delight.

"But," continued Pinero, "do you go unaccompanied into restaurants, or" - he laughed - "I was going to say gentlemen's clubs, but of course you couldn't."

"Why not?" queried Irene. She tilted her head back in a challenging way she had with men. She knew how to make herself look glamorous and inviting and available, and she could make men treat her as an equal. Look at the effect she had on poor old Dr Watson when she returned to London some years later and got involved with Sherlock Holmes! Apart from Watson, look at how she treated Sherlock.

I remember that night she was wearing a low-cut gown that must have cost somebody a fortune, for I don't think she bought it herself. It was deep crimson with a look of the House of Worth about it, and neither Gilbert nor Pinero could keep their eyes off her decolletage.

"Go on," she continued. "Why couldn't I go into a gentlemen's club disguised as a man?"

"You wouldn't dare," grinned Gilbert. "As soon as you took off your hat, the game would be up." He nodded admiringly at her luxuriant hair. "You can easily stroll the streets dressed as a man, Miss Adler, I dare say, because you've got the admirable cool cheek to do it. As long as you wear your hat, that is. But I doubt if you'd go further."

Irene leaned forward. "Would you bet on it?"

Gilbert contemplated her decolletage for about thirty seconds, then shook himself a little and met her gaze. She knew how to make the best of her fine eyes, too.

"How about a tenner?" he said. "No, wait. You'd have to crop your hair for it and I doubt whether you'd go that far for a tenner, so I'll make it worth your while. Twenty-five quid if you do it."

"Do what? Have my hair cut?"

"Not just that. Dress as a man and go into a gentlemen's club undetected. You'll have to do something, of course, before you come out. Let's see..."

"Make it guineas and you're on," said Irene, while he was thinking. "I'd have to buy a wig afterwards."

"Twenty-five guineas?" said Pinero, his bald head shining in the light. "I'll up it to fifty. But - Gilbert and I keep the hair." The decolletage and the eyes had affected him more than the voice had.

"It's a deal over the hair," said Irene. She turned to me. "Fancy it, Anna? Quick, while they're still prepared to lose their money."

"All right," I agreed. I had had half a glass too much. "I'll do it for fifty guineas."

"Just a moment," said Gilbert.

"Backing out?" asked Irene.

"No. But I've thought of that condition to make it worth the fifty guineas. Not only must you cut your hair, but if Miss Weybridge here is prepared to go with you, you must both play cards in the club - can you both play? Good. Let's say a hand of baccarat, whist, or bridge with two members. You could do that? And you must get away with it by remaining undetected throughout. Now that's worth a hundred guineas of two men's money."

"It's a bet," said Irene. We shook hands all round.

"So," I said innocuously. "We go into a club and play with two male members, eh?"

Gilbert almost exploded and Irene dissolved into laughter, while Pinero gave me a quizzical grin. I honestly didn't realise what I'd said, for even though I had been at the Royal Court for a year, I had preserved my innocence and from time to time it showed.

I knew little about men. I'd had admirers, stage door Johnnies and the like, but I had kept them at a distance. Irene was very experienced, I knew, and had had lovers. I had some grasp of the theory, for I had seen the farm animals while I lived in the States. Yet the practical side of what men and women did together remained a mystery to me. Although I didn't know it, I was soon to find out.

Gilbert knew someone who could get us into the Tankerville Club, and he and Pinero arranged the escapade. Irene and I had our hair cropped and fluffed our eyebrows up, and on impulse I dyed mine a dark blonde, both hair and eyebrows. Irene shook her head over it, but it was done and there was no going back. Too late I realised that I would have to hide my dark eyelashes with tinted glasses.

A couple of nights later, dressed in borrowed tails, I went with her and Gilbert's young acquaintance, dapper little George Grossmith, to the Tankerville. In my tinted glasses I felt like a member of a Continental secret society.

"We're going tonight because it'll be quiet," said George, who was in on the plot, "and if you can't find anyone to play cards with, I'll sit in with you and bring someone along. I dare say that will fulfil the conditions of the bet. I say, you don't have to win at cards too, do you?"

He was full of the adventure and thought it a tremendous lark. Irene and I had fortified our courage before setting out, for, as Irene said, she felt more nervous than she did on her first night at La Scala. As we were going in, we took each other's hand without thinking, but an agonised squawk from George brought us to our senses.

"For goodness' sake be careful!" he said. "Oh, and if you need to - er - to answer nature's calls, don't go looking for the ladies'. There ain't one."

George spoke to the doorman and ushered us into a quiet room where some card tables were set out.

"You don't smoke, I suppose," he said.

"I do," said Irene.

"Filthy habit," said George, offering her a cigarette. She lit it and relaxed in her easy chair, handsome with her short-cut hair and rather elegantly masculine in her tails. She looked like the sort of poetic young man who would go out and die for a cause in the Balkans or somewhere.

"Mm," she said, drawing in the smoke, "Sullivans. So far so good, Jack." That was my name for the evening. She was Bob.

She crossed her legs and lounged back like a man. I copied her, while George went off to try to find a couple of members who fancied a game of cards.

For a few minutes we sat quietly, although my heart was going fifty to the dozen and I think Irene's was, too, for all that she looked so cool. Suddenly a couple of men joined us. Both were heavily built and bearded, the shorter a good few years older than the other. The younger man was a giant, well over six foot, but very handsome. He must have been in his mid twenties.

George was nowhere to be seen. I was surprised when Irene rose to her feet and bowed.

"The Prince of Wales, Jack!" she hissed to me. I rose too, and bowed, feeling as though a hefty fist had hit me in the stomach. The Prince waved graciously at us and motioned us to sit.

"Are you the two guests of Mr Grossmith?" he asked. We nodded, too nervous to speak.

"I gather you're looking for someone to play a hand or two of baccarat, whist or something of the sort?"

"Yes, sir," said Irene, and I noticed the quiver in her voice. "But we can't afford high stakes, I'm afraid."

"We could play for a guinea a rubber," said the Prince.

"Why play for guineas?" asked the younger gentleman. "We could play for crowns."

"Crowns?" echoed Irene.

"Bohemian crowns," smiled the other, taking from his pocket a handful of coins.

"This is the Count von Kramm, of Bohemia," explained the Prince. We both bowed again. "Crowns, Kramm? Well, why not use them as counters? It will pass a pleasant hour."

We sat at one of the tables and began. It was indeed a quiet night, and we were alone in the room. It looked as though George had found no-one but the Prince and his friend to play with us. Although I was nervous, the shaded table lamp and dim lighting of the room helped to reassure me. The two men never seemed to doubt our assumed identity, but concentrated on the cards. As for Irene, she soon began to revel in the escapade. I could tell from looking at her.

The pair of us put up a good showing, but the Prince became bored and we changed to the relatively new game of bridge. I thanked my lucky stars that I had bothered to learn it. The Prince was my partner, and to my relief he proposed that we played just for the enjoyment of the game. He ordered champagne and after a glass or two my courage returned and I joined in the chat and jesting. I so far relaxed as to remove my tinted glasses.

Irene was obviously in her element. She told risqué jokes, gossiped about theatre folk, and even chaffed the Count, much to his amusement. At length we called a halt, and the Prince and the Count went to the lavatory. I was desperate to go myself, but dared not go with the men.

When they returned, the Count proposed a light supper in one of the small private rooms and rang for a waiter. Meanwhile Irene and I excused ourselves and visited the lavatory. In there I noticed a fine ring lying on the washstand. It consisted of a splendid single diamond set in a simple plain gold band and I was astounded that anyone could have forgotten it.

"The Prince was wearing it," said Irene. "We'll take it back to him, but right now, I'm bursting."

We passed the urinals and locked ourselves into the single W C cubicle.

"Look out, Anna!" said Irene as we manoeuvred to take turns on the bowl. "There's not enough goddamn room here to strangle a cat, let alone swing one."

"How the hell do you get these bloody braces off in a hurry?" I gasped, wrestling with the buttons. "Help, Irene, before I have an accident. I'm bursting too!"

Giggling and whispering, we struggled back into our trousers, and cautiously peeped out of the cubicle. The coast was clear, but the ring had gone!

"Oh God!" said Irene. "He must have come in while we were in there."

We had heard nothing, but then we had been making so much noise ourselves. Like fools, we had used our real names, but in any case the whispering and giggling must have given us away.

"Let's do a bunk," I said. "The game's bound to be up. Men don't go to the W C in pairs."

Irene giggled. "My God, Anna! You can be so deliciously naive. No. We'll go back and face the music. There's fifty guineas for each of us in this, and if I know Bertie, he'll think it's a splendid lark. The other fellow seems to have a bit of humour about him too. He laughed at one of my jokes, I remember. Actually, I think he's quite nice. He's certainly the right age."

We crept back and found our partners lounging with cigars. Irene accepted one, but I politely declined. My heart stopped momentarily as I noticed that the Prince was wearing his ring. If he'd collected it himself he must have overheard us.

However, he gave no sign of having heard anything amiss, and for a while the three of them smoked and chatted. I poured myself another glass of champagne and waited for the unmasking of the two shameless hussies who'd penetrated the Tankerville.

If I was nervous, Irene wasn't. She smoked her cigar like a trouper, coughed hardly at all, and kept up a flow of chatter. I knew by now that she'd had too much to drink, and I was terrified that she'd decide to give us both away out of bravado.

"The supper should be ready by now, surely," said the Count at length. "Where's the waiter?"

"Why don't we go down to the room?" suggested the Prince. "It's private, I take it? Good. After you, Kramm."

Irene accompanied the Count down a corridor, while the Prince and I followed. On the way, he took my elbow and halted outside a door.

"May I show you something rather interesting in here? Don't suppose you shoot big game, what?"

"I have done, in the States," I answered carefully. "Buffalo, I mean."

The Prince stared for a moment. "You having me on, young - young feller?"

"No, sir. I spent some years out there."

The Prince guffawed. "Good Lord! Well, I can't show you a buffalo skin, but what about this?" He led me into a small private room. "Now, isn't that a beauty? That beats buffalo, I'll wager."

A huge tiger skin rug occupied most of the floor. It certainly was a beauty. It must have been eight feet long, and the head had been stuffed and made up into a fine snarl.

"Very nice, sir," I said.

"Presented by Colonel Sebastian Moran, one of the members. Don't suppose you know him?"

I didn't. The Prince sat on a sofa and invited me to sit by him. No sooner had I done so than he placed a hand on my knee, smiled at me and said, "Now my dear, be a good girl and tell me your name."