Robert Mark, who died on Thursday aged 93, was Commissioner of the Metropolitan Police in the 1970s, when he made it his mission to eradicate corruption among detectives at London's Scotland Yard.
He also took personal command of two hostage situations, involving IRA terrorists at Balcombe Street and an armed gang at the Spaghetti House restaurant in Knightsbridge, which he judged the most dramatic and difficult siege since Sidney Street.
Hawk-featured and urbane, Mark dominated the Met for five years from 1972. A liberal image masked an authoritarian steel: he complained that the courts were too lenient; argued in favour of majority verdicts in jury trials; and excoriated corrupt lawyers who defended criminals.
Robert Mark was born on March 13, 1917, in the Manchester suburb of Chorlton-cum-Hardy, the youngest of five children.
His first job as a carpet salesman bored him, and in 1937 he applied to join the Manchester city police, to the dismay of his father, who protested that it was only one step better than going to prison.
Back in Manchester after the war, a series of rapid promotions landed him in the chief constable's office as chief superintendent in charge of administration, younger than the youngest inspector in the force.
On New Year's Day 1957, Mark took over as chief constable of Leicester. Dropped off in his new Ford Consul by his brother (Mark had yet to learn to drive), he was startled to discover that under the genial rule of his predecessor, staff at police headquarters went home for lunch.
Abolition of such excesses within the force was followed by more visible reforms; in 1961, to general acclaim, Mark cancelled an order for hundreds of parking meters and instead established a corps of traffic wardens administering a fixed penalty system.
When Soviet spy George Blake escaped from Wormwood Scrubs in 1966, Mark served on Lord Mountbatten's inquiry into prison security. On his return from a visit to Dartmoor, he was offered the post of assistant commissioner at the Met. He was appointed deputy the following year, and commissioner in 1972.
Mark's reign as commissioner coincided with heightened terrorist activity in the capital, particularly from the Provisional IRA. In 1975 alone 10 people were killed and 169 injured in a total of 29 bombings and other incidents.
These included the Balcombe Street siege, in which a gang of IRA gunmen -- "four seedy, cowardly degenerates", as Mark later described them -- took a couple hostage at their flat in Marylebone. Mark took personal command and put the SAS on standby.
Hearing this on the radio, the gang surrendered; the hostages were unharmed.
Mark's most surprising appearance as commissioner was in a series of television commercials for car tyres that ran from 1974. His wooden endorsement -- "I believe Goodyear tyres make a major contribution to road safety" -- ensured cult status for the campaign.
Robert Mark married, in 1941, Kathleen Mary Leahy, who died in 1997. Their son and daughter survive him.