Everyone knows what happened 950 years ago this month, don't they? William the Conqueror killed Harold and became King of England.
Not quite. Harold and the flower of his army died at Hastings on 14 October 1066. But the magnates of England then proclaimed Edgar the Aetheling as King.
Edgar the who? "A forgotten prince… but one of the builders of a new England" is how the historical novelist Stewart Binns describes him.
John Speed in his History of Great Britaine (1611) said Edgar was "In such esteem with the people, that he was called England's darling."
He "came close to winning back his throne and reversing the Norman Conquest… He deserves to be better remembered," says Martin Lake, who has written four novels centred on him.
But for most he really is a forgotten prince (Aetheling in Anglo-Saxon means prince).
While England forgot him, Scotland took his sister Margaret to its heart. As Queen she is credited with important reforms; as a saint her works of charity and the miracles of her shrine were recorded in great detail - some of them legendary, perhaps.
But where is Edgar's legend? There are many remarkable stories about him. That he led a party of knights errant into Italy - that he was showered with gifts by the Byzantine emperor, allegedly including an elephant. Legends have been built on less.
For a historian the stories need "ifs" and "abouts" and "perhapses" but for a legend they are fine.
In 1066 Edgar was about 14 and Margaret several years older. They were born in Hungary, where their father was exiled. He was brought back to England by his uncle King Edward the Confessor, but died soon afterwards.
The Confessor had no children. Edgar and Margaret, and their sister Christina who became a nun, were successors of the royal house of Wessex, descendants of Alfred the Great and of five kings after him.
After Harold died Edgar did function as a king; he endorsed a new Abbot of Peterborough, for instance. But he was young and the English leaders were disunited. They submitted to William and he was crowned.
In 1068, Edgar, Margaret and their mother and sister went to Scotland. One story is that they were heading for the continent and were blown off course. Well off course.
King Malcolm III married Margaret shortly afterwards. Did he have designs on England? It is striking that they gave their four eldest sons royal names from the House of Wessex - Edward, Edmund, Ethelred and Edgar.
Three of Margaret's sons became kings of Scotland, but her influence on the country was much greater. Her contemporary, Bishop Turgot, recorded that she summoned Church councils and argued for days against opponents of reform. She was clearly a formidable character, not sparing the rod for her children, and "feared by people while they loved her", Turgot wrote.
He tells how she fed orphans and paupers and washed their feet, embellished the royal court and erected a fine church at Dunfermline, where her tomb was venerated.
Many miraculous cures of visitors to Margaret's shrine were recorded and she was canonised in the 13th century.
Her name lives on in the chapel called after her in Edinburgh Castle and the capital's Queen Margaret University. Nearby North and South Queensferry commemorate the facilities she provided for pilgrims crossing the Firth of Forth.
In Dunfermline, says George Robertson, chairman of the city's historical society, the connection to Margaret is "part of the town - part of our life" and numbers of visitors seek the remains of her shrine and the cave where she is said to have gone to pray.
Margaret is "Somebody who through her own personal action or the inspiration which she placed within her family, has formed the whole nature of medieval Scotland and as a result transformed the cultural identity of modern Scotland" says Richard Oram, Professor of Medieval History at Stirling University.
Some have seen her as "the single-handed destroyer of all things Celtic in Scotland," he says, but "that was actually much more to do with reformation and post-reformation religious politics than the reality of the day."
During the 16th century the shrine was destroyed on the orders of religious reformers. Most of her remains, including her head which was kept as a holy relic by Mary Queen of Scots, are now lost. But a portion of her shoulder blade is venerated at the Catholic church named after her in Dunfermline.
And Edgar? In 1069 he joined northern English leaders and Danish invaders in a revolt which massacred the Norman garrison in York.
William bought off the Danes, put the English to flight, and "spent the whole winter in laying waste the country, slaughtering the inhabitants and inflicting every sort of evil without ceasing".
Back in Scotland, Edgar was eventually persuaded by Malcolm and Margaret to make his peace with William.
We do not know why William treated him so well, conferring on him, according to one chronicler, a pension of a pound of silver a day (of which Edgar allegedly blew a year's worth to buy a horse).
He outlived William - and Margaret, who died in 1093 shortly after her husband.
In 1097, says the Anglo-Saxon Chronicle, the Conqueror's successor, William Rufus, entrusted Edgar with an army to unseat Malcolm's brother Duncan II and place his own nephew and namesake on the Scottish throne.
But the chronicler Orderic Vitalis says Edgar was about this time taking part in the First Crusade, as was his friend Duke Robert of Normandy, the Conqueror's eldest son. Edgar apparently arrived with a fleet at the port of Laodicea (modern Latakia in Syria) in 1098.
Surely both these accounts cannot be wrong - if either or both are right it bespeaks a more vigorous and trustworthy character than Edgar is usually given credit for.
He fought on Robert's side in 1106 against the Conqueror's last son, who was by then Henry I of England. Henry imprisoned his defeated brother for life - but Edgar again got off lightly. He was now the Queen of England's uncle; Henry had married Margaret's daughter Edith.
No children of Edgar's are known. But the present royal family is descended from the ancient house of Wessex via both the English and Scottish royal lines, thanks to Margaret.
Eventually he seems to have retired. William of Malmesbury wrote in 1125 that the septuagenarian Edgar was "losing his grey hair quietly in the country". Perhaps on his Hertfordshire estates if he still had them. Or there is a suggestion that he died in Scotland. Perhaps he was buried near his sister.