In April 1954 the United States, the Soviet Union, France, Britain and China gathered in Geneva to search for a settlement to end the French military presence in Vietnam and recognise its independence. China was represented by its Foreign Minister Chou Enlai. Less than five years earlier the Chinese Communist Party led by Mao Zedong had seized power, forcing the defeated Nationalists (Kuomintang) led by Chiang Kai-shek to flee to Taiwan. For the United States the conference presented a great problem. For three years US troops had been fighting Chinese troops in Korea and Washington still recognised the Nationalists as the legitimate government of China.
At the conference John Foster Dulles, one of the most virulent anti-Communists of the Cold War not only refused to speak to speak directly to Chou Enlai, but also failed to shake his hand.
The story has entered the annals of diplomatic history and Richard Nixon in his famous 1972 trip to China is said to have apologised to Chou Enlai for the snub. (Kissinger called Chou Enlai one of the most impressive men he had met.) But rude though Dulles's behaviour was, even he was pragmatic enough to realise that the Chinese Communist government, recognised or not by the United States, had to be in the room.
It is a story worth remembering when there is still some hope that a conference in Geneva on the Syrian conflict, agreed in May by the US Secretary of State John Kerry and Sergei Lavrov, the Foreign Minister of Russia, might take place in the coming months. This despite the worsening situation on the ground which shows signs of spreading to neighbouring Lebanon and to the Golan Heights that separate Syria from Israel.
A regional war fought on sectarian lines between Sunni and Shia throughout the Middle East could be close. The urgency of at least establishing a diplomatic process grows by the day. It will not be easy, especially as there is no agreement as to who will participate in the conference.
Of course the five permanent members of the Security Council, the United States, Russia, China France and Britain, would be there, and the Assad government and the opposition. Other countries such as Germany, Turkey, Egypt and Saudi Arabia are also likely to be invited.
Whether Iran, the principal backer of the Syrian regime, will be there is unclear. On Thursday Mr Lavrov said in Moscow that he believed Iran must participate. But France and the United States are strongly opposed to the Iranian government's participation.
Iran and Syria have been strong allies since the 1979 revolution that overthrew the Shah. And there is no doubt that Iran is Syria's strongest political, economic and military backer.
UN sources believe it is currently bankrolling the Assad regime to the tune of $3-4bn a year. On top of this Iran is a steadfast backer of the Lebanese militia Hezbollah which is now fighting openly in Syria and may have been critical in the Syrian regime's recapture of the town of Qusayr.
Were Iran to be left out of the Geneva process there is little doubt that it would play the role of spoiler, a part it is particularly skilled at assuming. Western intelligence services have long had evidence that Iranian security personnel have been involved on the ground as advisers to President Assad's forces.
Almost 60 years on from the Geneva Indochina conference there is a danger that we seem to be losing sight of the purpose of diplomacy. Negotiating with friends and allies is never the challenge. The real diplomatic challenge has always been negotiating with those with whom we are diametrically opposed.
One of the most skilful diplomats to recognise this was the late Richard Holbrooke of the United States who negotiated with Slobodan Milosevic, the Serbian leader later indicted for war crimes, not once but twice: to end first the Bosnian War at Dayton, Ohio, in 1996 and then a few years later the Kosovo war.
As the situation in and around Syria deteriorates on an almost daily basis, the search for a diplomatic solution becomes ever more urgent. Attempting that without Iran would inevitably be dangerous. Forlorn though the hope is at the moment, Iran's forthcoming elections to be held next Friday, 14 June, might still produce some surprises – as happened in the last elections in 2009.
Between 2001 and 2005 I accompanied the then Foreign Secretary Jack Straw on several diplomatic visits to Teheran, for talks which focused largely on nuclear issues. Despite his efforts, the initiative yielded few concrete results, not least because of the visceral opposition of the Bush administration and a lack of support from No 10 itself.
For years, the West has pursued a dialogue with Iran focusing almost solely on the nuclear issue. Now Russia, without whom no peace in Syria is possible, has made it clear that it views Iran's participation in the Geneva process as essential. The West may yet have to yield on its objections to an Iranian presence in Geneva. But the United Nations and its tireless envoy, Lakhdar Brahimi, cannot afford to exclude Iran, as one of the largest countries in the region. The West may yet have to follow the precedent set by John Foster Dulles in Geneva in 1954.
Lord Williams of Baglan is Distinguished Visiting Fellow at Chatham House and the former UN Special Co-ordinator for Lebanon