As tributes to the former minister poured in last night, it emerged that Mr Cook had been climbing a remote mountain in north western Scotland with his wife, Gaynor, when he suffered a suspected heart attack at about 2.20 yesterday afternoon.
The couple were enjoying a secluded and gentle walk up Ben Stack, a 2,365ft mountain popular with hillwalkers which lies five miles from the coast, when he collapsed suddenly near the summit.
It emerged last night that a coastguard rescue helicopter scrambled from Stornaway in the Western Isles took some 30 minutes to arrive after Mrs Cook raised the alarm on the mobile phone of a fellow hillwalker. Meanwhile, she desperately tried to revive her husband, a keen hillwalker who was known for this love of the Highlands.
Guided by medical experts via telephone, the helicopter crew then fought for a further 40 minutes to save his life where he fell, using cardiac resuscitation as Mrs Cook looked on.
There were unconfirmed reports last night that the former Foreign Secretary had suffered serious injuries after he collapsed, and fell further down the mountain.
After they failed to revive him, the crew flew Mr Cook to Raigmore hospital some 70 miles away in Inverness, where their Sikorski helicopter arrived at about 4pm.
The former foreign secretary was pronounced dead at 4.05. He was 59.
His death was formally announced by Northern Constabulary nearly three hours later. It is thought the force waited until his first wife, Margaret, and their two sons had been informed.
"Mr Cook apparently took ill while walking with his wife Gaynor on Ben Stack and was removed by Stornoway coast guard helicopter to Raigmore Hospital in Inverness," a police statement said.
It is understood that Mrs Cook had to walk down the mountain because there was not enough room on the helicopter. A police report into his death will be prepared for the area's procurator fiscal, the Scottish state prosecutor - a routine part of the legal process in such circumstances.
Mr Cook, the Labour MP for Livingston, near Edinburgh, was a keen hillwalker, and regularly spent his summer holidays with close family and friends enjoying the dramatic mountain scenery of Highland Scotland rather than going abroad.
A keen sportsman, Mr Cook was also an avid race-goer and pundit who wrote racing columns for Scottish newspapers before becoming Foreign Secretary when Labour were first elected in May 1997.
In emotional tributes last night, Gordon Brown, the Chancellor, described Mr Cook as one of the "greatest parliamentarians of all time".
He was first elected to Parliament for Edinburgh Central in 1974, and then becoming the Labour MP for nearby Livingston in 1983. He became one of the most potent and vocal critics of the war in Iraq after resigning as Leader of the House of Commons on the eve of the invasion in March 2003.
A regular columnist for The Independent, he wrote trenchantly about the Iraq war and the row about whether Saddam possessed weapons of mass destruction. As a backbench MP, he kept up his attacks on Tony Blair's Middle East strategy and close political relationship with US President George Bush.
His resignation speech is considered one of the finest ever made in the Commons, and he had remained a powerful and influential voice until his death yesterday. At the last election, Mr Cook retained his seat, a Labour stronghold, with just over 50 per cent of the vote.
As Foreign Secretary in Labour's first term, he sought to implement a more ethical approach to Britain's relations with the rest of the world. Mr Cook himself had listed his proudest achievements in Government as: "Breaking the deadlock in the Lockerbie case; defending Kosovo; saving lives and relieving suffering in Sierra Leone; contributing to the fall of Milosevic; transforming Britain's relations with Europe; rebuilding respect for Britain in the world."
A leading figure in the Labour Party for decades, Mr Cook was put in the key job of Foreign Secretary when the party won power in 1997. After his resignation from the Cabinet in protest at the Iraq War in 2003, he repositioned himself as a supporter of the Chancellor, Gordon Brown, and made repeated calls for Tony Blair to step down as Prime Minister in his favour.
Mr Cook's devotion to enhancing the role of Parliament as Leader of the Commons made him a popular figure among backbench MPs, and his powerful resignation speech on the eve of war won him great respect from opponents of military action.
Mr Cook's death comes three years after a health scare that resulted in him being admitted to hospital after fainting in a central London restaurant, where he had been eating with his wife. Although his diary, published last year, avoided spelling out the nature of his complaint, it did refer to a consultation with a cardiac specialist.
He wrote on his discharge from hospital: "St James's Park has never looked more lovely or the tourists more cheerful. There is nothing like a mild intimation of your mortal frailty for reminding you of the beauty of life."