The Anglo-French-Israeli invasion of Egypt 50 years ago aimed at retaking control of the Suez Canal is widely seen as a catastrophic miscalculation which proved disastrous for British interests in the world.
The then British Prime Minister Anthony Eden usually gets the blame, but in the view of historian and biographer Andrew Roberts, he was the subject of a betrayal that changed the course of history.
Eden was "stabbed in the back by an unscrupulous cabal"
The modern-day analogy of a prime minister called Anthony committing British troops in the Middle Eastern theatre in the face of much domestic opposition is too obvious to be laboured, although it is noticeable that Tony Blair seems to have learnt from Churchill's dictum: "We must never get out of step with the Americans - never."
If only Eden had paid more attention to the sensibilities of the Eisenhower administration as it faced the 1956 presidential elections, much might have gone differently.
Certainly Eisenhower himself years later admitted that not supporting Eden over Suez had been his greatest foreign policy mistake.
The Left have long held Suez was "no end of a lesson", arguing that the adventure proved Britain could not act without the imprimatur of the United Nations any longer, and that Anthony Eden fell as a result of his unhinged demand for unilateral - or bilateral with France - action against Nasser's perfectly justified demand for an asset that was built on the sweat of the Egyptian peasantry.
There is another version. This one puts British national interest priority over high-minded liberal internationalism.
Its heroes are not the Labour leader Hugh Gaitskell, First Sea Lord Lord Mountbatten and Liberal Lady Violet Bonham Carter - who opposed the Anglo-French "police action" - but the right-wing Tory MPs Julian Amery, Captain Charles Waterhouse and Fitzroy Maclean, who supported it.
The revisionist view holds that Eden was absolutely right to resist the unilateral and practical confiscation of Britain's greatest single overseas asset, that had been bought in hard currency by Benjamin Disraeli in 1875.
On the eve of victory, just as General Hugh Stockwell telegraphed Downing Street to say that within 48 hours the entire Canal Zone would be in British hands, Eden was stabbed in the back by a cabal of unscrupulous Cabinet colleagues, short-sighted allies and a small and unrepresentative group of Tory liberal internationalists.
It is undoubtedly true that Suez tragically proved that Britain was no longer a Great Power, but this was their fault, not Eden's.
The cabal - by threats and falsehoods and leaking - forced Eden to call a ceasefire only days before Stockwell's objectives of Ismailya and the town of Suez were attained.
If the Suez operation had succeeded, Nasser would probably have fallen, like many discredited anti-Western adventurers.
This would not have preserved Britain's status indefinitely but it would certainly have slowed the scuttle of the Western colonial powers from Africa and Asia.
Over-hasty decolonisation, which brought vicious civil wars and dictatorships to much of Africa over the next three decades, might have been avoided.
Nasser would probably have fallen had the invasion succeeded, says Roberts
Had the "informal empire" system, by which American and British companies shepherded the Arab oil economies towards mutually beneficial co-operation, not been dealt such a blow at Suez, the vicious oil price hikes which did so much to dislocate the Western economies in 1973 might have been blunted or even prevented.
In October 1973 a barrel of oil cost $3.02. By December it was $11.65 because OPEC suddenly quadrupled prices virtually overnight.
The result was a huge economic downturn for the West and disastrous ripple effects for the rest of the world.
Embers of Suez
There was nothing inevitable about Muslim fundamentalist and Arab nationalist victories in places like Iran, Iraq and Libya in the 1960s and 1970s.
Britain had regularly put down such revolts, such as those of Arabi and the Khalifa, ever since Gladstone's original invasion of Egypt in 1882.
Yet after 1956 she was in a far weaker position to protect Arab rulers from revolution.
The coup in Baghdad on 14 July 1958 saw the murders of both King Faisal II and Prime Minister Nuri-es-Said within two years of their advice to Eden to "hit Nasser hard and quickly".
The subsequent history of Iraq, and especially her recent history, would have been very different if Nasser had been toppled.
The embers of Suez took a long time to cool in Britain, especially on the Right where it resuscitated a strain of Tory anti-Americanism that had not been much in evidence since the 1920s.
Even as late as in November 2004, after David T Johnson of the US Embassy in London had said that America had historically been prepared "to stand by your nation, through thick and thin", a letter appeared in The Times consisting of only one word: "Suez?"