Historians have uncovered evidence that the English believed William Wallace wanted to be King of Scotland.
Accounts of King Edward I's Exchequer for 1304-1305, describe the Scots patriot as someone who "falsely sought to call himself King of Scotland".
Researchers described his find as "startling" but urged caution, saying the English may have misinterpreted Wallace's role as Guardian of Scotland.
Wallace was hung, drawn and quartered in 1305 for high treason.
He led the Scots to a victory over English forces at Stirling Bridge in 1297 as part of a struggle for independence.
Dr Reuben Davies, from Glasgow University, made the discovery as part of a study, funded by the Arts and Humanities Research Council, into cross-border society and Scottish independence during the years 1216 to 1314.
Researchers from the universities of Edinburgh, King's College London and Lancaster were also involved.
Accounts of King Edward I's Exchequer, known as the "Pipe Roll", describe Wallace as, "a robber, a public traitor, an outlaw, an enemy and rebel of the king, who in contempt of the king, throughout Scotland had falsely sought to call himself King of Scotland."
Dr Reuben Davies said: "In the pipe roll for the financial year 1304-1305, there is an entry which has until now gone unnoticed - it is the account for expenses incurred in the execution of William Wallace and for taking his quartered body to Scotland.
"The financial account is also made up of a descriptive account of Wallace's crimes, the manner of his death, and the fate of his dismembered body.
"The record shows quite vividly the extent to which English civil servants saw Wallace's trial and execution as an extraordinary event, so exciting that they broke from their usual routine to note down the details in what would normally be a dull and dry record of income and expenditure."
Dr Reuben Davies said the pipe roll was "a new source for the trial and death of Wallace" and included "the otherwise unrecorded indictment that, 'he had falsely sought to call himself King of Scotland'".
He said the view presented in Scottish histories had always been that Wallace never sought the Scottish crown and had never called himself King of Scotland.
This view, until now, has not been explicitly contradicted in English sources.
The researcher said, however, that the pipe roll account should be treated with "caution".
"Wallace was always scrupulous, in the very few documents issued in his name, to say that he acted on behalf of King John Balliol," he said.
"The pipe roll may not be a credible source for the notion that Wallace actually sought to call himself King of Scotland.
"The accusation could, in fact, signify English incomprehension of Wallace's role as Guardian of Scotland.
"The English perspective of Wallace's time as sole guardian, when he did what a king would have done - issuing writs and appointing bishops, for example - could have been that he behaved like, and therefore called himself, King of Scotland."
A full account of the research by Dr John Reuben Davies can be found at the Breaking of Britain project website.