THERE I WAS, Roger Tubby of 151 Milbank Avenue, in white tie and tails, sitting at dinner to the right of Marie Jose, the queen of Italy. No matter that she was the former queen of Italy, that she had been born a Belgian, that she was nearly blind. She was still slight and pretty and vivacious, an elegant hostess there in the long dining room of her ch.ateau in the Swiss countryside.

Others at the table besides my wife I don't remember except that there were a couple of Swiss bankers, a French count and some former Balkan royalty.

I was not there because of my social standing or wealth. I had none of either. I was there because I was the new American ambassador to the European Office of the United Nations and to Other International Organizations, which did seem rather impressive, I thought.

The evening was a welcome break from my conferences in Geneva on world trade, health, disarmament sumptuous, served by liveried waiters in Renaissance costumes and wearing white gloves. There seemed to be one waiter for each guest.

The tall silver candlesticks, the beautiful chandelier above, the big silver bowl centerpiece of flowering bulbs from the queen's greenhouse, the gold service platters, knives, forks and spoons, all were impressive and beautiful. The light anecdotal conversation in such a setting made for a delightful evening.

There was general sympathetic laughter when someone told a story about the time Mrs. Dean Acheson had dinner in Lisbon with the king and queen of Portugal and, on rising from the table to go into the drawing room of the palace, caght the hem of her long gown on the leg of the heavy dining room chair as she walked away. Her gown parted and fell to the floor. Imperturbable, the then secretary of state continued out to the drawing room in her slip. The gown was gathered up, and soon thereafter she was back in it as if noth

"Mr. Ambassador, have you had any embarrassing moments?" the queen asked with a sweet smile.

"Many, many," I said, and there was an expectant hush the length of the table. "Oh, do tell us just one!" her majesty exclaimed. Perspiration bathed my brow, but I began anyway:

WELL, THERE WAS the time I was returning to America on the old Mauretania (that was a touch of class, but I did not mention I was in tourist class). The last night out there was to be dancing after an evening of skits, and a boxing bout. There was a pretty redheaded girl and whom I wanted to impress, so I volunteered to box three rounds, if the other fellow was about my size. I said this cockily in her presence to the person in charge of enterment for the evening. "You see," I told her, "I used to box at Yale." I didn't tell her I wasn't a very good boxer. Nevertheless, I figured the worst that I could face would be another college boy and that our encounter would be in the nature of a sparring match, no vicious blows struck, just some fancy footwork, weaving and ducking, a bit of clowning.

There was a slight roll of the ship when I climbed through the ropes and was shown my corner around which were clustered some of my new shipboard friends, including the redhead.

I heard one of them say, "Look at the bum: you can take him out with a couple of punches."

I turned and looked across the ring. There was a man in a black silk robe doing knee bends with his gloved hands on the ropes. I could hear him snorting. He had a towel over his head. On the back othe robe were big red letters: BOOM BOOM.

Boom Boom? "Yeah, that's Boom Boom Kid Kaplan, the welterweight contender," one of my friends said, laughing. "He's been over in Europe knocking out the champions of Britain, France and Italy."

At this point in my tale I turned to the queen and said, "Yes, your highness, even the champion of Italy." She smiled graciously. Perhaps I should have stopped there and left the rest to the imagination of those around the table. Clearly they'd already gotten the idea as to why this incident was embarrassing, but I was emboldened by the excellent wine.

The referee gestured me to the center of the ring. Coming across to meet me with a dark scowling visage, a flattened nose and a cauliflowered ear was Boom Boom.

The referee instructed him to go to a neutral corner when there was a knockdown. Meanwhile, Boom Boom was tapping his gloves together while giving me the most baleful stare. Then I had an inspiration. I'd tell him that this was a gag, that it was nice meeting him and I wished him well next month when he'd fight for the world title, and I'd pat him on the shoulder and get the hell out of the ring.

"Touch gloves and come out fighting," the referee said.

The bell clanged for Round 1. Boom Boom rushed across the ring. I noticed his heavily muscled sloping shoulders, the bulging biceps, his bobbing shuffle. I remembered that about all I had had at college was a fast, sharp, straight jab.

I hit him with the jab on the top of his forehead. He probably hardly felt it, but down he went. Excitedly, the referee led me to a neutral corner. He began counting over Boom Boom, who was now on all fours shaking his head. My friends were whooping and hollering.

Boom Boom staggered to his feet at the count of eight. He wobbled. "Kill him," someone shouted. But I knew better. Boom Boom had put on his little act, and now he would show how a professional dispatches an amateur: boom, boom and out!

He got in close, crowding me against the ropes. He grabbed by arms, clinched, then whispered, "Relax, bub, we'll give 'em a good show." And I guess we did. He was down a couple more times, even going through the ropes, but he rocked me with his left and right hooks. He was fast and powerful. I saw stars, though he was probably pulling his punches. My nose bled. At the end of three rounds my lips were puffy.

SUDDENLY, as I was describing the action to the queen, I felt a wetness on my chest. I looked down. On my white boiled shirt front was a red stain, spreading. I felt no pain. Nevertheless, I knew I was shot. Probably a killer with a silencer on his gun, aiming through the window. I could see the headline: Another American Ambassador Assassinated.

And then I realized that in describing the fight, I'd been gesticulating with a glass of red wine in my hand, which had spilled over me.

Embarrassing moments? I held a napkin over the stain, like a Masonic apron, held it there during the coffee and brandy and cigars. As ranking guests that evening we departed early, though protocol dictates that royalty give the sign for departures.

The redhead? Taking one look at my face, and my near- closed eye, she said, "Roger, you look awful. You better go to bed."