LONDON, JUNE 13 -- Prime Minister Margaret Thatcher began her third term in office today by reshuffling her Cabinet, recalling Cecil Parkinson, who resigned from her administration in 1983 amid a sex scandal.

Parkinson's return from the political wilderness came as Thatcher changed 11 of 22 slots in the Cabinet, rewarding officials who were seen as having contributed to her reelection on Thursday and downgrading others. Parkinson, a star of Thatcher's first administration, will serve as energy secretary.

Thatcher did not change the major officers of state overseeing foreign and home affairs or the chancellor of the exchequer.

The return to the Cabinet of Parkinson, 55, reportedly caused unease among several senior government figures. He has long been a Thatcher favorite, despite the scandal that erupted shortly after he masterminded her 1983 campaign, when it was learned he had had an extramarital affair with his secretary, which resulted in a child.

Parkinson replaces Peter Walker, considered the last Tory moderate in the Cabinet, who was relegated to head the relatively inconsequential Welsh Office.

Thatcher's new Cabinet was announced late this afternoon after hours of suspense. Reporters stationed outside the prime minister's official residence at 10 Downing St. watched in vain for clues on the faces of the Cabinet members, who arrived and left in quick succession.

Once the officials all had been personally informed of the changes, Thatcher visited Queen Elizabeth II to obtain her ceremonial approval. On a day marked by royal pomp in addition to the political events, Queen Elizabeth had spent the morning watching the "Trooping of the Color," the annual outdoor pageant that marks her "official" birthday for the nation.

The queen, who was 61 on her real birthday in April, broke with royal tradition by attending the ceremony in a bright blue and white dress, carrying her own umbrella and traveling in a carriage. In the past, she had worn a military uniform and ridden sidesaddle on a horse.

The Cabinet changes included five resignations, most notably that of Norman Tebbitt, a controversial figure considered the leading Tory hawk, who remains as the powerful chairman of the Conservative Party.

Tebbitt served in the Cabinet as chancellor of the Duchy of Lancaster, a "nonportfolio" sinecure usually allocated major responsibilities by the prime minister. He reportedly asked to be relieved of his Cabinet duties to spend more time with his wife, who is confined to a wheelchair from injuries sustained when Irish terrorists bombed a hotel at the 1984 party conference.

Kenneth Clarke, the former paymaster general and second-ranking employment official, became Lancaster chancellor. Clarke has been assigned to coordinate a government initiative designed to revitalize Britain's failing inner cities.

The other departures included Lord Hailsham, 79, whose resignation as lord chancellor, the chief justice officer in charge of the country's courts, ended a long and distinguished political career in several Conservative governments. He was replaced by former attorney general Michael Havers. Michael Jopling, who had enraged British farmers by curbing subsidies, was replaced as agriculture minister.

The most politically significant resignation, however, was that of John Biffen as Conservative leader in the House of Commons. A popular figure, Biffen incurred Thatcher's wrath on several occasions in recent years by publicly indicating he disapproved of what he considered her authoritarian style of management.

It had been widely rumored that she would fire Biffen after the election. Several weeks ago, he told reporters he would rather walk out of the Cabinet on his feet than "crawl out" on his knees. This apparent reference to the political oblivion into which most Thatcher rejects have disappeared was taken to mean he would remain an active figure on the parliamentary back benches.

Trade and Industry Secretary Paul Channon was demoted to transport secretary. Former employment secretary Lord Young was elevated to replace Channon, reflecting Young's closeness to Thatcher and his active role in the recent campaign.