The Times is changing. News reporting is more aggressive; presentation is much more lively. Familiar names and flowery writing are disappearing from opinion columns.

Behind the scenes, entire departments of business managers are being replaced. New printing technology is being introduced, and cost-cutting moves are being made.

This is almost revolutionary change for Britain's most famous national newspaper. It also was notably staid and unprofitable before its purchase, along with its sister Sunday Times, earlier this year by Australian publisher Rupert Murdoch.

Murdoch is better known here for the nude pinups and racy style of Britain's most popular and profitable papers -- the tabloid Sun (3.8 million circulation daily) and News of the World (4.4 million each Sunday) -- and in the United States for his remaking of the New York Post with a similarly sensationalistic style to increase its circulation from 500,000 to 750,000.

Murdoch has moved into a seventh-floor office in the Times building here to personally direct an all-out effort to make his new acquisition profitable after years of heavy losses and to prove in the words of one Times executive, "that he can publish a quality newspaper."

The takeover of the Times and the disputed purchase of Britain's oldest and best known Sunday newspaper, the Observer, by another unorthodox empire-builder aroused considerable controversy here. The influence of the Times (just over 300,000 circulation), Sunday Times (about 1.4 million) and Observer (about 1 million) far exceeds their readership, and the British establishment believes their independent editorial control as well as financial survival is vital. The deals have been debated in Parliament and subjected to government review, including an antitrust investigation that has delayed the purchase of the Observer by Roland (Tiny) Rowland for up to three months.

What happens to these papers also could have a far-reaching impact on Britain's 14 other national newspapers, which are published by eight different owners and are being forced to compete for a shrinking number of readers. The combined circulation of the dailies declined by 400,000 during the last half of 1980, and the total weekly sales of the Sunday papers fell by 1.4 million.

Although their proprietors are secretive about their balance sheets, a number of national newspapers are losing money or barely breaking even, according to industry analysts. Notoriously ineffective management and combative, feather-bedding labor unions have made Fleet Street, the publishing district of London, a difficult place to make a profit, except for the biggest selling, lowest overhead tabloids. Owners of the Times and Observer, in particular, had been expected to pay dearly for the prestige of being philanthropic patrons of the establishment press.

Yet Murdoch and Rowland, according to associates, intend to be active publishers and eventually produce a profit.

Murdoch moved swiftly to streamline his acquisition and cut costs. He fired an army of business and marketing managers, and he told remaining executives that he wanted to move the Times out of the building it rents from the Lord Thomson conglomerate and consolidate its offices with the Sunday Times in the building Murdoch owns across the street.

He failed to get everything he wanted in negotiations with the 54 union "chapels" that represent the two newspapers' 4,000 employes. But Murdoch won a reduction of 563 jobs during the next six months and immediate introduction of computerized printing technology that Thomson's managers were never able to uncrate because of union opposition.

"Board meetings take half an hour now and are full of decisions," said one Times executive who welcomed Murdoch's decisiveness. "They used to take all day and produce a lot of cigar smoke but no decisions."

But the biggest question about Murdoch's takeover of the venerable Times was what he would do to its editorial content.

What most of Murdoch's newspapers have in common is their reflection of his increasing political conservatism. He has turned the New York Post around 180 degrees politically, using it to support right-wing candidates the way his Australian newspaper crusaded against liberal politicians there.

To satisfy critics when he bought the already conservative Times and to avoid an antitrust inquiry by the government as the owner of four British national newspapers with a combined circulation of 10 million, Murdoch agreed to a number of strict conditions, the violation of which would be a criminal act punishable by a prison sentence. They guarantee the independent appointment of outside directors and working journalists to the Times board and preservation of the newspapers' editorial independence.

Harry Evans, the award-winning editor of the Sunday Times who was moved next door to Murdoch to edit the Times, said he has been given complete control of editorial personnel and content. He has instructed his staff to treat Murdoch's business interests in the news columns just as they would anyone else's.

"Murdoch has demonstrated a belief in the paper backed up by money and personal involvement in its business management," said Evans.

While reluctant to discuss the changes he is making, Evans said he was trying to avoid shocking loyal Times readers. The newspaper remains both the notice board and sounding board of the establishment, with its prestigious letters-to-the-editor columns, chronicling of royalty and high society, extensive verbatim accounts of parliamentary proceedings, and summaries of legal decisions that are admissable as evidence in English courts.

But one of a number of senior editors, writers and contributors who are leaving the paper or losing their old positions complained that the brighter, newsier Times was slighting its unique traditional commitment to commentary, ideas and intellectual discourse that had been emphasized by Evans' predecessor, William Rees-Mogg.

"Yes, it was donnish and elitist," achnowleged this journalist. "That was its special role. Rees-Mogg ran it almost like a commons room at Oxford. Harry Evans is a newsman and he wants only the hot news."

The turmoil at the Times is small compared the reaction of journalists at the Observer to its sale to Rowland, Britain's most acquisitive entrepreneur, by Robert Anderson of Atlantic Richfield Oil (arco). Rowland wants to add the Observer to his fast-expanding Lonrho mining, distilling, retailing, publishing and investment conglomerate.

Because of the strong opposition to his purchase of the Observer, Rowland failed to avoid an antitrust inquiry even though he tried four different ways of buying the newspaper to escape the clutches of Britain's Monopolies Commission. Rowland's associates say business leaders and bureaucrats resent his success while others have fallen on hard times here.

Rowland's Lonrho conglomerate was already undergoing an exhaustive antitrust investigation into his stormy struggle to take over the House of Fraser, Britain's largest and most prestigious retailing chain, crowned by Harrods department store. The takeover is being fought fiercely by the House of Fraser's board of directors.

Beginning, like Murdoch, with only a small, family-owned property, the 63-year-old Rowland built his fortune on a base of shipping and mining investments in Africa through tireless, often contentious and sometimes shadowy wheeling and dealing. His close personal involvement with various African leaders and revolutionaries, his stock-trading and financing methods, autocratic management habits and his frequent board-room battles have not endeared him to the conservative men who run Britain's financial community or those who run the government bureaucracy.

Rowland has commanded strong loyalty from small stockholders and employes in his ventures and has depended on their support to win tough takeover fights. But he has had a difficult time convincing outsiders that rather than being a speculator in stocks with a paper empire, "I believe in assets, in land, in factories, and stores."

Rowland's purchase of the Observer was unusually secretive. Anderson of Arco never told the Observer board that he was selling.

Shocked and angry directors, editors, and reporters at the Observer said the sudden sale followed Anderson's failure to place his friend, Observer journalist Kenneth Harris, on the Observer board, and the recent departure from Arco's board of director believed to be the Observer's "protector." They wrote angry letters to the Times, and editor Donald Trelford published an editorial in the Observer headlined "Unacceptable," that called Rowland's takeover "discourteous," "ill-advised" and "the unacceptable face of multinationalism."

Observer journalists, who did not want to be quoted by name, accused Rowland of trying to avoid an antitrust inquiry so he could not be forced into binding quarantees of editorial independence that Murdoch accepted. They said they believe Rowland wants to use the newspaper to further his other business interests, particularly in Africa, where the Observer is perhaps the best known Western paper. They claimed knowledge of Rowland's intention to review all stories about Africa.

Rowland's opponents pointed out that the Observer has been notably critical and skeptical in its reporting of Rowland's business activities in the past. They said they hope that the antitrust inquiry will provide time for another buyer to make a better offer to Anderson and Arco.

Also refusing to speak on the record, an associate of Rowland called the journalists' charges "absolute rubbish." Rowland wanted to avoid a Monopolies Commission inquiry, he said, only because he did not want to bear its great expense at the same time as the investigation of his attempted takeover of the House of Fraser.

Rowland's real interest in the Observer, said his associates, is its econimic potential. Its presses are now used only one day a week for the Observer, offering the opportunity to print another newspaper on them daily.

"We believe," said Lonrho's chairman, Lord Duncan-Sandys, in a statement to stockholders at Lonrho's annual general meeting here recently, "that in a variety of ways the profitability of the Observer could be appreciably improved, while preserving its editorial independence and unique character, to which we attach the highest importance."

"We will judge," said a skeptical senior Observer journalist, "by any guarantees of editorial independence that emerge from the Monopolies Commission inquiry. There is still a lot of anger and apprehension here."