The Battle of Hastings changed the course of history
Banks warn customers not to choose 1066 for their credit card pin number.
So well known a date in British history is it, that identity thieves know they'll get a good return from trying their luck with it.
But why is it such a memorable year? It's because we know that when William the Conqueror ended the reign of the last Anglo-Saxon king Harold at the battle of Hastings, things were never the same again.
Regime change was enforced, outsiders took over, land was redistributed, castles were built. Not many people would quibble with calling 1066 a true turning point year, when tangible change was effected.
The signing of the Magna Carta bound King John to obey the law
Likewise the repulsion of the Spanish Armada in 1588 and the battles of Bosworth (1485) and Culloden (1746). Following these military entanglements, the political landscape was decisively altered.
But history is about more than battles and wars. Small moments build on one another and don't always have such an obvious pivot point.
So is it possible to identify those longer-term social changes by plucking out the years that signify and exemplify them? It is.
For instance, 1851 was the year of the Great Exhibition at Crystal Palace. Did much change in the world as a result of this mighty celebration of Britain's industrial supremacy? Perhaps not, though it did kick-start the apparatus of the modern tourist industry.
The industrial revolution - a turning point that is harder to pin down
What it did do was exemplify the idealism and optimism of an age when technology and industry seemed to be creating a better world. 1851 is a more oblique turning point, but one that captures a broader movement of progress toward an industrial globalised world.
Similarly the Peasants' Revolt of 1381 did not achieve much there and then.
No statute abolishing serfdom led directly from the rising of downtrodden peasants against the depredations of their masters.
But the magnitude of the rising did destroy the complacency of the English ruling classes. In that sense, demonstrating as it does the movement toward a more equitable society, 1381 is just as much a turning point as 1066.
The BBC History Magazine asked historians from across Britain to nominate their key moments, the results of which are now being published in the book The Great Turning Points in British History. Two give their arguments for their chosen dates below.
THE BLACK DEATH OF 1348 by Professor Mark Ormrod
The Black Death of 1348-9, and subsequent outbreaks of plague between the 14th and 17th Centuries, transformed both the society and the landscape of Britain.
Within a generation it reduced the population by half - the biggest human tragedy ever suffered in these islands.
The Black Death is thought to have killed half of Britain's population
But by altering the balance between people and resources, it also resulted in a major redistribution of wealth down the social scale.
This turned a peasant economy into a proto-capitalist one, and paved the way for the agrarian and industrial revolutions of the 18th and 19th Centuries.
It prompted the huge shift toward pastoral farming that made British wool one of the greatest economic commodities in Europe and, in due course, turned Britain into a nation of clothmakers.
It shifted the population away from the countryside and towards towns, sponsoring the manufactures and trade that served the new prosperity of the lower orders.
And it inscribed itself onto the topography of Britain in the form of derelict villages, isolated country churches and the ubiquitous hedgerows that enclosed former commons and open fields.
The Black Death defined the social and cultural fabric of Britain for four centuries, and was one of the formative influences on the emergence of the modern commercial economy.
THE CRISES OF 1956 by Professor Pat Thane
Most significant was Britain's ignominious withdrawal from Suez, condemned by the UN and, particularly, by the US for the invasion. This drove home the point that Britain was no longer a first-rank world power.
The Suez Crisis spelled the end of the British Empire as a great power
So did the visible crumbling of the Empire. Often violent independence movements were going on in Malaya (leading to independence in 1957); Cyprus, where serious negotiations about independence began after Suez; Kenya, where the Mau-Mau rising was in progress. The Gold Coast became independent Ghana in 1956.
At home things were more cheerful. In 1957 Harold Macmillan said, famously: "Most of our people have never had it so good." He was right. There was full employment and living standards rising as never before, owing much to Clem Attlee's post-war Labour government.
But a better-off, better educated population was less deferential. Easter 1956 saw the first protest against nuclear arms, leading to the formation of CND in 1958. The "Angry Young Men" began attacking what they saw as the stifling conventions of the class system. Colin Wilson's novel The Outsider was published in 1956 and John Osborne's play Look Back in Anger was first performed.
Women were angry too. A campaign had led to equal pay in the public sector in 1955 and there was protest at women's unequal work opportunities.
The 1950s was not quite the dull, grey decade that's often thought.
Not convinced by the arguments? Tell us which moment in British history you consider a turning point using the form below.
1066 in which England was invaded, the signing of the Magna Carta by the King of England, the English Peasant's revolt, the Spanish Armada opposed by the English navy, and the battle of Bosworth field, which changed the monarch of England, are events in English history not British. Scilla Cullen, Hitchin
14 June 1645, at Naseby, the history of the country and the world changed course with the overthrow of autocratic royal government. Martin Marix Evans, Blakesley, Northants
1688 saw the Glorious Revolution when James II fled in the face of William of Orange's army. James's overthrow began modern English parliamentary democracy: never since has the monarch held absolute power, and the Bill of Rights has become one of the most important documents in the political history of Britain. David, Petersfield, Hants
A year that I consider to be a turning point in British History in 1532 when Henry VIII broke away from the Roman Catholic Church and subsequently made Britain a Protestant country. If he had never done this we would all still be Roman Catholics obedient to the Pope. This event gave Britain her independence to decide what was morally and ethically acceptable practices for her population, despite the fact that interest in religion has declined in recent years, this was still a highly significant event in our history. Karen Gay, Wrexham
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