Popperfoto / Getty Images

Detectives inspect the Royal Mail train from which over 2.6 million pounds was stolen, on Aug. 8, 1963, in Cheddington, Buckinghamshire, England.

LONDON — The mastermind behind Britain's "Great Train Robbery," a 1963 heist that turned its perpetrators into celebrities, has died at age 81, local media reported Thursday.

Bruce Reynolds died in his sleep at his home in London after a period of ill health, reports from news media including the BBC said, citing comments from Reynolds' son, Nick.

Paul Popper / Popperfoto / Getty Images

A photo issued by Scotland Yard on Aug. 2, 1963, shows Bruce Reynolds, who has died at home in London.

His death came just months before the 50th anniversary of the Great Train Robbery, which was at the time Britain's largest robbery.

In August 1963, Reynolds, along with an 11-member gang, tampered with railway track signals and stopped a Royal Mail night train travelling from Glasgow to London carrying letters, parcels and large amounts of cash.

Reynolds and his men stormed the train and made off with 2.6 million pounds, equivalent to about 40 million pounds or $61 million in today's money.

Train driver Jack Mills was struck over the head during the robbery. He died seven years later, and many people believed the injuries he sustained during the heist contributed to his death.

Most of the gang members were caught and given prison sentences totaling more than 300 years, but Reynolds evaded capture, fleeing Britain with his wife and son. He spent five years as a fugitive in places as far afield as Canada and Mexico.

On his return to Britain, Reynolds was caught by police and sentenced to 25 years in prison, of which he served just 10.

Reynolds later found fame as an author after penning his memoirs, titled "Autobiography of a Thief." 

His accomplice Ronnie Biggs achieved similar notoriety after he escaped from the prison where he was serving a 30-year jail sentence for his part in the robbery.

Biggs spent 36 years on the run, leading a playboy lifestyle in South America, before finally surrendering to British police in 2001. Biggs was freed in 2009 on health grounds.