Some people were quite sober. Patrick Mayhew, the Secretary of State for Northern Ireland, for example, stayed completely erect, despite being so tall and carrying what always looks like such a heavy head, so filled with judiciousness and wisdom, and so readily inclined to bend down and listen, wisely and judiciously, to what Irish people and the servants have to say to him. He and Peter Snow from Newsnight were the tallest people in the room, and you could use them like lighthouses if you had lost your direction in the crowd and had forgotten where, or who, you were.
At the bar a couple of us fell in with, or into, a man from Co Cork, who began to whisper in an urgent kind of way: "Now, do you not think I'm the very image of T P McKenna?"
We didn't quite catch the name. "Tee-Pee- Mac-enn-ah, the faymous I-rish ack-tor," said our new friend, whispering still but with Tiny Tots hyphenation. "You know he and I look so alike I'm often mistaken for him."
"Oh," I said, "you mean T P McKenna, the famous Irish actor."
"Sssh!" said the Cork man. "He is the gentleman with his back to you. I'm going to introduce myself. Would you like to meet him?"
This is the kind of thing that happens at parties: a man who thinks (quite wrongly) that he looks like T P McKenna introduces himself to T P McKenna solely on these grounds, and brings along a couple of strangers to witness the introduction.
T P behaved heroically, sized up the awkwardness of the situation in a glance, and began to talk about the place of James Joyce in Irish literature, and the worth and beauty of his short stories, which brought about the second kind of thing that happens at parties. You wish to participate, even to please (and especially actors); you wonder what to say.
Now where had I last seen T P McKenna? In The Charge of the Light Brigade as Howard Russell - or Russell Howard, or William Howard, or Howard Johnson - no, the last is an American chain of cheap hotels; in any event, as the reporter from the Times who covered the Crimean war?
But even if that was right, it was 25 years ago - 25 years in which Mr McKenna had no doubt been giving splendid performances in other films and plays, which it now become important for me to remember. And now - salvation! - he was talking about Joyce's Dubliners.
"I remember," I said, creepily, "that you gave a terrific performance in the John Huston film of The Dead, which I think is the best film version of Joyce that's ever been made."
T P stopped for a moment. "No," he said, "I wasn't in that, that was an American thing." The words suggested a film on a par with cheap-hotel chains. "I was in Ulysses." Some moments later, and quite rightly, he said he was going home.
THAT is the third kind of thing that happens at parties, the words of disengagement that so often prove false. "Well, must go, babysitters and all that" or "I'll be back, just getting myself another glass of wine", and then minutes later you see the same person enjoying themselves (and surely enjoying themselves more?) with another group of people - the babysitter or the promise of return completely forgotten. But at the best parties, such as the Irish embassy or any other that goes on long enough, disengagement and re-engagement stop being a problem. Animated groups seem simply to form and re-form themselves around you with the speed and abruptness of dreams.
Suddenly I was talking to Clare Short, Labour's front-bench transport spokesperson, and falling in love. I don't mean this in the lustful sense - the fourth kind of thing that happens at parties, the girl I heard at the bar saying "I'm going to get wildly drunk" as her partner's fist clenched her bottom - but rather in the way that you might with a town on top of a hill in Italy or the discovery of a very good book.
Ms Short was lively and open, qualities not found in many prominent politicians and for good reason (see all the trouble Ms Short got into for her mild speculation about the need to reform cannabis legislation).
The clincher, the moment at which feelings of interest changed to undying admiration, came when I was asking her about Labour's plans to undo railway privatisation, which every day throws up new examples of folly and ruin and sheer Majorite pigheadedness. I am not quite sure (are you?) what Tony Blair means when he promises to refashion a "publicly accountable" railway system. So what was Labour going to do, precisely?
Ms Short talked about investment and quality and the need to make trains things to be proud of and useable again, which was all good news. And then, sensing residual scepticism, she said: "Look, we'll do exactly what you would do!"
You? Me! What I would do! How odd it is that politicians make so little use of that warming and infinitely wise idea. For a few seconds, I heard the sound of steam pistons ("like a pencil-box shutting", as a friend once said to me, though that analogy is now as archaic as the noise on the incline), and saw carriages painted sensibly in dark maroon, and smelt the pipe-smoke clinging to the rough-cut moquette of the second-class compartment. Then our man from Co Cork reappeared and stared ominously at my heroine.
THIS is the fifth and last kind of thing that happens at parties. In vino veritas, the need to unburden yourself of the truth. Our man, who was in some department of public relations, wanted to tell Ms Short something that would help her. It was this. She should cheer up on television. He said that she sounded too grievous, that her mouth went down at the corners (here he pulled his own mouth into a sad clown's shape), that she should lighten up.
Ms Short, who may have heard all this before, put up with him for a while, and then she asked him to change the subject. He did not. Then she asked him, gently the first time, firmly the second, to go away. He would not.
What was I (you! me! the railway consultant!) to do? Ms Short is a Strong Woman, after all, and has been a Strong Woman since long before the Princess of Wales cottoned on to the fact that the term described more than housemaids who could be trusted to carry heavy household objects such as breakfast trays. It seemed sensible to let her sort it out for herself, until she turned and said: "Could you please make this man go away?"
You? Me? Of course I could. I did. Ms Short thanked me, and then we drifted apart, dream-like.
The Irish embassy party is the best I have ever attended. I hope yours is as equally filled with affection and swollen hearts of gallantry.