Jack Slipper, 81, the tenacious but frustrated Scotland Yard detective who personified the worldwide hunt for the Great Train Robbery fugitive Ronnie Biggs, died Aug. 23, it was reported in London. In recent years, he had suffered from cancer and a stroke.

Mr. Slipper was known as "Slipper of the Yard" -- sometimes "Slip up of the Yard" -- to the millions who followed the Biggs chase from England to France to Australia to Brazil in the 1960s and 1970s.

Biggs had a minor role in the 1963 robbery of the Glasgow-to-London mail train, a flamboyant action that netted his gang the equivalent of more than $50 million today. The tall, craggy-faced and dapper Mr. Slipper was among the special team of detectives who trailed and caught most of the gang.

Biggs was sentenced to 30 years in prison, which he viewed as unjust and vowed to escape. He did so brazenly in 1965, by daylight, and traveled around the world, usually just a step ahead of the police. He settled in Rio de Janeiro and began a relationship with a samba dancer named Raimunda.

The tabloid newspapers loved Biggs's extravagant and bawdy lifestyle, and to many at the time, he symbolized rebellion against authority. His followers, including the British punk rock band the Sex Pistols, made him a legend. He sang on their recording "No One Is Innocent."

A London Daily Express reporter who had planned to interview Biggs tipped off Mr. Slipper to the rendezvous in a Rio hotel room in January 1974. The detective knocked at the door and seemingly had his quarry.

Mr. Slipper reportedly told him: "Long time no see, Ronnie."

They also exchanged thoughts about the pub scene back home. But any jocular discussions soon grew into a diplomatic tangle.

Raimunda was pregnant, and as the expectant father of a Brazilian dependent, Biggs could not be deported. A memorable photograph appeared in the British press showing Mr. Slipper beside an empty seat on his return flight to London.

There were other attempts to bring Biggs back, including a disastrous attempt by British mercenaries in 1981 to spirit him to Barbados, a British commonwealth. At the time, Biggs was quoted expressing fondness for his Scotland Yard adversary: "We've always been friends. I'd like to have a few beers with him, but only in Brazil."

Jack Kenneth Slipper was born in London's East End on April 20, 1924. He was an electrician's apprentice and served in the Royal Air Force during World War II, becoming a noted boxer.

He joined the Metropolitan Police Service, known as Scotland Yard, in the early 1950s. Within a decade, he joined the "flying squad" that investigates armed robberies in London. He also had a role in the apprehension of those responsible for the grisly murders of unarmed London police officers in 1966, and he helped instigate the first "supergrass" trials, involving the use of underworld informers. After retiring in 1979 as detective chief superintendent, Mr. Slipper became a security consultant, played golf in celebrity tournaments and wrote a memoir, "Slipper of the Yard" (1981), which went out of its way to dispel the tabloid image of a dogged loser.

In 1990, Mr. Slipper accepted a libel claim settlement of 50,000 pounds from the BBC. The broadcasting company had aired a television film about the pursuit of Biggs that made Mr. Slipper look incompetent -- in his words, "the fall guy in an Ealing comedy to entertain the public at my expense."

In retirement, Mr. Slipper said he viewed Biggs as "a villain and a cunning monkey" but also saw no advantage in his imprisonment.

"I cannot believe the general public, who seem to have accepted the Great Train Robbers as folk heroes, would want it," he told the Daily Mail in 1992. "I have a certain amount of respect for the way he has handled himself and fought to remain free."

Physically ailing, Biggs made a much-publicized bid in 2001 to return to England a free man and was quickly deposited in Belmarsh jail in London.

That year, Mr. Slipper told a British reporter: "I look back on the whole thing with fondness because, in a way, Ronnie made me famous and you do get philosophical in your old age. But it has been a lifelong saga. And when Ronnie does return and is brought to justice, it will mean my wife Anne and I can enjoy some peace of mind.

"I have been ill myself and I am older than Ronnie. It would give me great satisfaction to outlive him to show that my way of life was best in the end."

Survivors include his wife; two daughters; and five grandchildren.

Biggs is in a prison hospital and still hopeful of a pardon.

Jack Slipper, best known for his pursuit of Ronnie Biggs to Brazil, also investigated other armed robberies and the murder of London police officers.