Jeremy Thorpe, in 1967, waving his hat as he drives away from the House of Commons after being elected leader of the Liberal Party. (Keystone/Getty Images)

Jeremy Thorpe, a magnetic English politician who restored the fortunes of the Liberal Party in the 1970s but whose trial for conspiring to kill an alleged male lover led to one of the most spectacular falls from grace in British public life, died Dec. 4 at age 85.

His death was widely reported, but complete details were not disclosed. He had Parkinson’s disease for more than 30 years.

Mr. Thorpe won a seat in the House of Commons in 1959, when he was 30, and began to take the message of the once-moribund Liberal Party around the country. He campaigned by helicopter and hovercraft, invariably dressed in well-cut vested suits and a narrow-brimmed trilby hat.

A 1979 Washington Post article noted that he was “Britain’s most dashing young politician,” with higher approval ratings than the leaders of the country’s two dominant parties, Labor and the Conservatives.

He was a charismatic campaigner and orator, known for a gift of mimicry and devastating comments about political rivals. In 1962, after British Prime Minister Harold Macmillan dismissed several members of his cabinet, Mr. Thorpe quipped: “Greater love hath no man than this, that he lay down his friends for his life.”

Mr. Thorpe’s Liberals (now known as the Liberal Democrats) had been in eclipse since the rise of the Labor Party in the 1920s. After becoming party leader in 1967, Mr. Thorpe advocated a range of liberal policies that boosted the Liberals’ support throughout the country. He advocated Britain’s entry into Europe’s Common Market and called for a withdrawal of support for racist regimes in South Africa and in Rhodesia, now known as Zimbabwe.

In February 1974, the Liberals won almost 20 percent of the vote in a national election. The strong showing meant that neither the Conservatives nor the Labor Party won a parliamentary majority, which left Mr. Thorpe holding the balance of power. He rejected an offer to serve in the cabinet of Conservative Prime Minister Edward Heath, saying he would not compromise his political principles.

Heath then resigned, which opened the door for Labor leader Harold Wilson to become prime minister, working in coalition with Mr. Thorpe’s Liberals. In October 1974, Labor won an outright majority in another parliamentary election. After only eight months near the pinnacle of power, Mr. Thorpe and his party were again on the political margins.

Even worse for him, a long-simmering personal scandal came to light. For years, a onetime stable groom named Norman Scott had said he had been Mr. Thorpe’s gay lover in the early 1960s, when homosexual acts were still a criminal offense in Britain. Scott sold his story to newspapers — one headline read “How Jeremy Seduced Me” — and letters surfaced in which Mr. Thorpe referred to Scott as “Bunnies.”

Mr. Thorpe repeatedly denied that he had had any romantic involvement with Scott.

In 1975, a man named Andrew Newton went on trial on gun charges after taking Scott to a moor in Devonshire, the same region Mr. Thorpe represented in the House of Commons. Newton drew a gun and killed Scott’s dog, a Great Dane, then pointed the gun at Scott, but it did not fire.

After Newton spent two years in prison, he said he had been hired by associates of Mr. Thorpe’s to kill Scott. Mr. Thorpe also fell under suspicion for allegedly funneling money from Liberal Party coffers to a private fund to silence Scott.

A former member of parliament, Peter Bessell, told investigators that he regularly relayed payments from Mr. Thorpe to Scott in the 1960s. Moreover, he said, Mr. Thorpe had openly talked about having Scott poisoned, thrown down a mine shaft or encased in concrete.

“It is no worse than shooting a sick dog,” Mr. Thorpe supposedly said, according to Bessell.

After the investigation, Mr. Thorpe and three other men were charged with conspiring to murder Scott. The six-week trial in 1979 became a tabloid sensation.

Mr. Thorpe and the other defendants were acquitted by a jury. Mr. Thorpe’s wife and 76-year-old mother sat beside him in the courtroom every day of the trial.

John Jeremy Thorpe was born April 29, 1929, in London to an aristocratic family. His ancestors had been prominent in British legal and political circles since the 14th century, and his father was a barrister and Conservative member of Parliament.

As a child, Mr. Thorpe was stricken with tuberculosis, and his family isolated him in a private cottage with medical attendants for most of a year. In 1940, he and a sister were sent to the United States for safety during the German bombing of Britain in World War II.

He returned to England in 1943 to enter the exclusive private school Eton, where he won awards as a promising violinist. He also told classmates that he would one day be Britain’s prime minister.

At the University of Oxford, from which he graduated in 1952, Mr. Thorpe was president of the Oxford Union, a debating society that is often a springboard to politics, and was known as a dandy who collected porcelain and gave elaborate parties.

He practiced law in London for several years and was a frequent commentator on radio and television in the 1950s before winning his first election to Parliament. After his political career was destroyed, Mr. Thorpe retired from public life but continued as an eminence grise to the Liberal Party. In a 1999 autobiography, “In My Own Time,” Mr. Thorpe said nothing about the scandal that brought about his downfall.

His first wife, the former Caroline Allpass, was killed in a car accident in 1970, two years after they were married. Their son, Rupert Thorpe, announced his father’s death to the media.

In 1973, Mr. Thorpe married his second wife, the former Marion Stein, a onetime concert pianist known as the Countess of Harewood, who died in March. She had previously been married to a British earl who was a cousin to Queen Elizabeth II.

About to stand trial in 1979, Mr. Thorpe ran for reelection to the House of Commons. No one was surprised when he lost.

Mr. Thorpe dryly commented that the accusations surrounding him had “hardly helped.”