Contrary to popular expectation Le Tout London has gone bananas over the queen.

It has been a rather hideous blow for the cynics who had not expected anything of the sort.

But a sense of national pride has overcome even the most jaded sophisticates who, in the last few days, have been virtually frothing at the mouth with raves for Queen Elizabeth and her Silver Jubilee.

At first nobody knew exactly what the popular stance was supposed to be so everybody who was anybody, (i.e. everybody who had a house in the country or friends with a house in the country) disappeared. Last weekend, from Saturday through Tuesday night, London, socially, was a ghost town. Intellectuals, jet-setters and the nobility were nowhere to be found, though the streets were mobbed with tourists and middle-class Britons who had gathered from all over the island to watch the queen's procession to the service at St. Paul's Cathedral.

But Wednesday the telephones were buzzing. The columnists, commentators, London insiders and socialites and decided that the queen was wonderful. There would no putting down of the monarchy this 25th Jubilee.

They had thought to ease into their approval. It took time. They had to make sure they weren't going to come out in favor of the queen and be left standing alone. So the acceptance took several stages.

The first was to criticize all of the anti-Jubilee reporting which had been done locally. "Really," said one London intellectual, "it was so overdone and they all took the monarchy soooo seriously. If you're going to criticize the queen it shouldn't be done so solemnly."

The second phase was to damn the queen with faint praise. "Of course the royal family is not chic," said a British lord."They've have looked down upon for centuries by the true aristocracy as boring, dull and coarse. George the Fourth was the last chic member of the royal family and he died in the mid-19th century. Of course, there was Queen Victoria's oldest son, Edward Seventh. At least bogh of them were trendsetters."

But even this man, after a few moments of consideration had to concede, "I suppose it really would be ghastly if the queen were a trendsetter, or a jet-setter. But the worst thing would be if she were a fashionable intellectual like we are. That would be the pits."

And finally there were numerous disclaimers from well-known columnists who treated the jubilee like a confessional and admitted that though they had been putting down the queen for years, now that they thought about it she really was terrific.

By mid-morning Wednesday it turned out that everybody who had been away ("Wouldn't dream of staying in London over Jubilee weekend" was the byword) had been glued to their TV sets in their country houses, knew every detail of the entire proceedings and had spent the whole weekend participating in their little village Jubilee celebrations.

"Of course," they would all say, "we did it for the children. It was such fun for them."

In fact, it became clear by Wednesday that the only people in London who were down on the queen or the Jubilee were the Communists and even they had a sense of humor about it.

The Communist national daily. The Morning Star, ran a picture Wednesday morning of two streetworkers cleaning up a pile of horse manure with brooms after the queen's carriages had passed by. Yachting on the Thames

Once Le Tout London had hit town they saw to it that they made up for lost time over the weekend. And they had to prepare for the big day Thursday when the queen would spend the entire day on her yacht touring various piers up and down the Thames, then watch a fireworks display from the Shell Building Thursday night before retiring to Buckingham Palace to wave once more from the balcony to the hysterical masses of adoring subjects waiting in the streets below.

Interestingly, parties are out in London, or at least, entertaining on a grand scale with butlers behind every chair is out. There are only two balls this season, which is extremely rare. One is what is called the "last debutante party which will ever be given" at Marlboro and the other is a prenuptual ball given at Claridges for a trendy young titled couple. For one thing most of the British don't have enough money to entertain lavishly any more, or if they do they are so terrified of calling attention to themselves because of taxes that they try to keep low profiles. Therefore it is no longer chic to be known as a hostess.

Where to spend Thursday evening watching the fireworks was the object of most conversations Wednesday and there was a lot of last-minute hustling to get properly placed.

Meanwhile Wednesday night there was only one place to be.

Lord Weidenfeld (Sir George), the famous publisher, gave a buffet dinner party in his apartment overlooking the Thames on Chelsea Embankment.

The party was in honor of Barbara Walters, who was covering the Jubilee for ABC, but she didn't show up until the end of the evening because she was working late.

Among the American guests were Evangeline and David Bruce, who are spending the season in London, Joe Alsop and Irwin Shaw, and Mr. and Mrs. Jack Heinz (ketchup mogul and Sen. Heinz's father) and producer Sam Spiegel.

British author Antonia Fraser was there without her friend, playwright Harold Pinter, which raised a few eyebrows. It seems that until recently they would never go anywhere without each other, would call their hostesses beforehand and ask to be seated together and then hold hands the entire evening.

London millionaire Jimmy Goldsmith was there, as were endless numbers of titled men and beautiful women.

Everybody was talking about the queen.Mostly about how they hadn't expected to like the Jubilee and how surprised they were and how the queen really was a jolly sort once you got to know her. One member of the House of Lords even went so far as to say that he once had dinner with the queen in a group of six or eight and that she was "The funniest person I've ever met. Jolly good sense of humor." Watching the Fireworks

Thursday, during the day, was really much more tiring for the queen than Tuesday and it was colder and rained. She had to ride up the river and get on and off her yacht, constantly visiting various piers and talking to the crowds. Yet she was much more relaxed in a far better mood than she had been Tuesday at St. Paul's. Even the stauchest queen-supporters had to admit that Tuesday she had seemed a bit down in the mouth. The general rationalization here is that she either was so moved at the service that she looked grim trying to control her emotions or that she felt sick.

She was dressed better on Thursday for her marathon yacht day than she had been in her pink Hardy Amies Tuesday. She wore a blue sailor outfit by Ian Thomas and matching hat during the day and a yellow Hardy Amise coat and dress for the evening. All very downplayed. The queen herself decided not to have anything new made for the Jubilee in a gesture of frugality in recognition of the unfortunate economic situation in England today. To appease her designers she will make Hardy Amies a Companion of the Victorian Order today when her honors lists are announced.

By 3 p.m. Thursday the queen good-naturedly slogged her way through crowds with her umbrella and her bouquet and her smile, greeting pensioners and centenarians and children and officials until there weren't any and then she went home to the palace to have tea and change for the fireworks.

Now Thursday, and where to watch the fireworks (which turned out to be beautiful but minor compared to Fourth of July fireworks and mostly unseeable because of rain and fog) became crucial.

There were four key places to be. The first was in the Shell Building with the queen and the royal family if you were on the Jubilee committee.

The second was on the John Heinz's launch, which they used to cruise up and down the river. There were other launches but that was the key.

The third was in any number of warehouses on the river which are being converted into artists' studios and apartments and where the new Foreign Secretary David Owen and the new ambassador to Washington Peter Jay live. (It's recently been dubbed "warehouse chic" and has overtones of the "redneck chic" brought in by the Carter administration.)

The fourth was the roof of the Savoy Hotel or any number of private rooms overlooking the Thames and where many of the visiting prime ministers are staying for the commonwealth conference. 'The Little Duke'

The 24th floor of the Shell Building was reserved for the royal family to view the fireworks (mainly because of its key location overlooking the river). But the queen, Prince Philip and Prince Charles did make an appearance on the 23d floor first to thank the 100 or so members of the Jubilee committee who were being wined and dined themselves. The princes were accompanied by Lord and Lady Drogheda, the head of the Silver Jubilee and the ubiquitous Duchess of Grafton, mistress of the robes and the tough cookie who keeps unruly commoners away from the queen.

The staff, in their white uniforms and nametags, were lined up to be greeted by the royals. Prince Charles, seeing that the tiny head chef was named "Duke," burst out laughing and asked the tongue-tied cook what they called him. The prince finally relieved the silence by suggesting, "the little duke."

Most of those who were at the party had maintained a healthy skepticism about the queen until she arrived, at which point they couldn't curtsy deeply enough or ooze loudly enough about how wonderful she looked and how exciting the Jubilee was. The queen took it all in stride and after a few brief moments disappeared with her family to watch the festivities alone.

Meanwhile, over at the Savoy, while the celebrities and prime ministers were closeted off in their private river-view suites, the diners from below were being made to sign indemnity cards in order to go up to watch from the roof.

Richard Harris, Rod Stewart, Britt Ekland, Chita Rivera, Zero Mostel and Rod Steiger were all hidden behind closed doors, having their own private Jubilee parties, as was James Mancham, the just-deposed president of the Seychelles. Social Climbers' Scramble

But back to the Heinz party. The Heinzes spend a lot of time in London, particularly during the season, and they do a lot of entertaining. Le Tout London is still talking about the party they had last year where they served all Heinz products "out of tins, my dear, can you imagine, said one chic Londoner.

At any rate, invitations to the Heinz parties are generally very sought-after, especially by the social-climbers who invade London at this time of year. So when they all got back from the country Tuesday night they began calling up to see if they could get asked on the launch. What many didn't know is that Drue Heinz's social secretary, Mrs. Roberts, is known to many as the most severe woman in London and has reduced even the thickest-skinned climbers to tears.

So as each unsuspecting person would call the Heinz house Roberts would inform them that Drue Heinz was much too busy to talk to them, that who were they anyway, that she had never heard of them, that simply everybody was calling to ask to get in and that there was just not room for "another body on board."

Drue Heinz had invited Women's Wear Daily to come and bring a photographer but Jack Heinz threw them off the boat when they arrived.

It was pouring rain and freezing cold so a tarpaulin had been placed over the top above the tables and chairs to keep the rain off and hot tea was being served when the lucky few invited arrived at 5 p.m.

Evangeline Bruce was there, the Duke and Duchess of Bedford, the Duke and Duchess of Rutland, David Hockney, George Weidenfeld, Lord and Lady Carrington, David Metcalfe, Sir Christopher and Lady Soames, Lady Anne Tennant, Douglas Fairbanks Jr. and Antonia Fraser with Harold Pinter (together again). Small heaters were set up to keep the guests from freezing to death for the next five hours but it was still pretty cold, and there was also some minor confusion because another launch had pulled up beside the Heinz's and the guests from that were having to climb over the Heinz boat to get on and off theirs. Comparing Notes

At any rate, yesterday morning, as people were comparing notes as to what they had been doing the night before, the general consensus was that being on a launch was miserable. "Be thankful," said one depressed partygoer to another less lucky. "You were spared."

Today is the last day of the big Jubilee week, though the festivities will continue to a lesser degree for the rest of the year. Of course, next is Royal Ascot with the grand finale being Ladies Day on Thursday when the queen will appear and everyone will wear grand hats and morning coats.

Today the queen will read off a list of honors and will review the guards.

The queen's Silver Jubilee has been, for all practical purposes, a public relations exercise for England during a much reported economic slump. Regardless of how it began and what the original attitude of most Britons was, particularly the critics of the monarchy and the cynics, there is no way today to say that it has been anything other than a raging success.

"Believing in, accepting and celebrating the monarchy," explained one softened cynic, is the same moral principle as believing in Christmas.But we all do it, don't we?"

"Just think," said a member of the nobility over a glass of champagne at George Weidenfeld's party the other night, "in all reality this will probably be the last Silver Jubilee England will ever have. Even if Prince Charles became king tomorrow, I can't imagine that in the year 2000 they will still be celebrating monarchies."

After this week, however, one shouldn't be too sure.