What was going on when I was born?

Trafalgar House P.L.C., the real estate and construction company that owns the Cunard Line, bid more than $450 million today for control of the Peninsular & Oriental Steam Navigation Company, one of the world's oldest and best-known shipping companies. P & O's directors immediately rejected the offer, calling it ''derisory and in no way reflecting the earnings potential of P & O or the strength of its underlying assets.'' Many analysts in the City of London agreed.

IT may be hard to believe, but the summer season really starts this weekend. Beach and country houses are officially opened, guest lists are being drawn up, the barbecue grill is being cleaned, and parties and entertaining are on many minds. Nobody ever seems to have absolutely everything that's required to face the summer in style and comfort, so we've collected an assortment of the little things that can add to the fun. Some are supremely practical, others are a touch luxurious, but all were chosen because they are good looking as well as functional.

Two seminary presidents, each of whom has left a vivid personal imprint on his institution, are stepping down after writing celebrated but distinctly different chapters in theological education. James I. McCord, a robust native Texan whose deep raspy voice still has a trace of a drawl, is leaving his post on June 1 after 24 years as president of Princeton Theological Seminary in New Jersey. At the Princeton seminary, an independent institution founded in 1812, Mr. McCord has upheld and, in the opinion of many, strengthened a long tradition of cultivating a learned Presbyterian clergy for a largely prosperous, established church. On June 22, George W. Webber of the New York Theological Seminary, on West 29th Street, will officially end 14 years of shaping an innovative curriculum for mostly black and Hispanic students that is widely considered the country's boldest theological program. Mr. Webber, a shy, self-effacing minister of the United Church of Christ, brought the seminary back from near collapse. Different Aims and Styles Colleagues are lavish in their praises of both men. Dr. John W. Beeners, a member of the faculty at the Princeton seminary, said of Mr. McCord: ''He is a cultivated, sophisticated, strong leader. I think he's even a greater pastor and friend than an administrator.''

RMINDA du PONT served caviar, tenderloin of beef salad and marinated mushrooms with Dom Perignon from the trunk of a brown Rolls-Royce. Blair Both had a cold three-layered mousse of tomatoes, chicken and sorrel along with cream of asparagus soup. She kept them cool in the shade of a 1934 Buick - complete with rumble seat - that had belonged to Louise du Pont Crowninshield. Susan Fraley and several friends wore straw garden-party hats and served their cooperative tailgate picnic on a table covered with a Madeira cutwork cloth. Such elegance was in evidence on a recent warm, breezy day at the Winterthur Museum and Gardens near Wilmington, Del., where hundreds of tailgate picnics dotted the gently rolling grounds. It was the sort of spring day that has unfortunately been in short supply, when the white and pale-pink blossoms on the dogwoods shimmer in the sunlight, the deep-red flowers of the azaleas are in full bloom and a large, inviting greensward seems the ideal place to dine. As luxurious as the food and surroundings seemed, however, most of these dishes were not prepared by professional chefs but by home cooks who simply like to cook and to picnic.

The Supreme Court ruled today, 8 to 1, that racially discriminatory private schools are ineligible for Federal tax exemptions. In an opinion by Chief Justice Warren E. Burger, the Court said there was no question that the Internal Revenue Service was correct when, in 1970, it stopped granting tax-exempt status to discriminatory schools. President Reagan sought last year to revoke the 1970 policy because, he said, it had ''no basis in law,'' in that there was no specific ban written in the revenue service code. This action came to symbolize his Administration's break with the civil rights policies of the recent past.

With an unabashed outpouring of affection, New York celebrated the 100th anniversary of the Brooklyn Bridge yesterday. It had been billed as a great day in the history of the city, and that is exactly what it turned out to be. In the morning, thousands of pedestrians, horse-drawn carriages and marching bands - filling the air with martial music - paraded across the stately bridge under summerlike skies. Later there were street fairs, speeches, roof parties, boat rides and a harbor-craft parade. Evening fell gently over the bridge. As darkness came, a luminescent full moon filled the sky while a dramatic sound and light show was played on the bridge and recreated its history. Then the sky simply exploded with fireworks. Red, white and blue shells, golden comets changing to silver, crackling stars in red and green, appeared to fill the entire sky, while hundreds of thousands of people gasped at the sheer dazzle of it all.

''The Government has a fundamental, overriding interest in eradicating racial discrimination in education, discrimination that prevailed with official approval for the first 165 years of this nation's history.'' - Chief Justice Warren E. Burger. (A22:6.)

NE day in the future some chronicler of our epoch will pin down the exact day when white wine overtook martinis at some of the better bars and hotels. A pivotal date if there ever was one, it marks the point in time when white wine moved up from its picnic-on-the-lawn image to a full-fledged succorer of shattered egos, bruised ids and thwarted ambitions. Most white-wine drinkers, whether at the ''21'' Club or in their own backyards, think of it as just that: white wine. Occasionally, someone will tell the waiter, ''I'd like a glass of chablis,'' but for the most part, no one other than the experienced enthusiast ever differentiates among the hundreds of different white wines on the market. It is ordered like a martini, with only an occasional inquiry as to exactly what is in the glass. But there is a great deal going on in the white-wine field, and it helps to know what's happening. To begin with, there is plenty of it around, thanks mostly to the Italians. What's more, a lot of it is pretty good. Not great, but good. About a decade ago, an unsung genius in the Italian wine business decided that it was time to find out what people wanted - as opposed to the time-honored French way: ''This is what we do; take it or leave it.'' The Italians threw out centuries of tradition - they had always made heavy, overoxidized white wines - and came up with new, fresh, lively wines that anyone could drink.

The Government's top health official said today that the investigation of acquired immune deficiency syndrome had become ''the No. 1 priority'' of the United States Public Health Service. Dr. Edward N. Brandt Jr., an Assistant Secretary of Health and Human Services, said the Government was taking steps in an effort to identify the cause and find a cure for the mysterious illness, known as AIDS, which leads to a breakdown of the body's immune system against disease. Dr. Brandt announced six new research grants for study of the ailment and the approval of a new heat treatment for blood products, through which some scientists believe the infectious agent might be transmitted. At a news conference, Dr. Brandt also said he was urging state and local health officers to report all cases of AIDS. He said the Federal Centers for Disease Control had stepped up surveillance of the disease. Since June 1981, the centers have received reports of 1,450 AIDS cases, of which 558, or 38.5 percent, resulted in death. Among the 78 cases diagnosed at least two years ago, the fatality rate was 82 percent.

Like many executives, William R. Rhodes likes to take a run around the reservoir in Central Park when time permits. But since last summer, Mr. Rhodes has not had much free time. And the word ''workout'' has taken on an entirely different meaning. ''Last August I was on vacation in Quebec City when the phone rang early one morning,'' he recalls. ''It was the office, telling me the Mexicans were in trouble.''

Higher prices for gasoline, housing and food helped raise the Consumer Price Index six-tenths of 1 percent in April, the biggest increase since last July, the Labor Department reported today. However, most analysts said the rise, which was twice the average monthly advance for the period from September 1981 through March, did not signify any worrisome revival of inflation that some have feared could erupt as the economic recovery gathers strength. Rather, it was regarded as an aberration resulting in part from the 5-cent-agallon increase in the Federal gasoline tax on April 1. ''This figure does not provide cause for alarm and does not indicate a long-term upward shift in the inflation rate,'' Martin S. Feldstein, the chairman of the President's Council of Economic Advisers, said in a statement.

Yasir Arafat sat smiling tonight under a photograph of himself surrounded by equally jovial commanders of the Yarmouk brigade. In a bantering humor, the chairman of the Palestine Liberation Organization dismissed a mutiny among a handful of his commanders down the road -in a place called Ait el Fukha - as a bit of mischief by Col. Muammar el Qaddafi of Libya and Palestinian radicals gathered around a renegade known as Abu Nidal. ''All of them are about 150,'' said Mr. Arafat in his enthusiastic but imprecise English. ''Now the head of this problem is Qaddafi. You can go anywhere in the Bekaa, in Tripoli. All the troubles they are exaggerating.''