Humbledon, a small village, on an eminence, under which a great victory was obtained by Henry Lord Percy, and George Earl of March, over the Scotch under the command of Archibald Earl of Douglas, on Holyrood-day in the harvest, 3 K. Henry IV, 1402. Earl Douglas's forces consisted of 10,000 men. He possessed the hills, but Lord Percy, sirnamed Hotspur, cutting off his retreat to Scotland with the plunder he had acquired in Northumberland, he was forced to come to an engagement on the plain. With him were most of the barons, knights, and gentlemen of Fife and Lothian, who escaped by flight, 22d of June, the year before, from the battle of Nisbet, in the Merse, in which fell most of the Lothian-youth. A great part of them were either slain or taken prisoners. Among the latter were the Earls of Fife, Murrey, Angus, Atholl, and Monteith. Earl Douglas received five wounds, and lost an eye. Five hundred Scotchmen in the pursuit were drowned in the Tweed. The field of battle is called Red-Riggs, from the blood spilt on it. By the side of the road, under Humbledon-Bauks, is an upright pillar of whinstone erected in memory of it; in height, six feet, six inches, and a half; in diameter, twelve feet.
From v2 of 'The natural history and antiquities of Northumberland' by John Wallis (1769). It sounds so dreadful that it doesn't seem unreasonable to want to appropriate the stone as a memorial.
An earlyish mention of the legend, and it's sort of interesting that there's another stoney place involved in the story:
We now turn southward on the Etall-road from Cornhill, about two miles from which, on the right hand, in Brankston-west-field, is a large upright pillar, of whinstone, six feet, seven inches high, and thirteen feet in diameter towards the base; a memorial of the great victory obtained over K. James IV, of Scotland, by the Earl of Surrey, on Friday, 9th of September, 5[sic] K. Henry VIII, 1513.
This battle is called, The battle of Brankston, from the chief scene of action being near that village; also the battle of Floddon from the Scotch intrenchments being on Floddon-hill, out of which they were drawn forcibly, as it were, to an engagement, by the Earl of Surrey's cutting off their retreat homewards. Among the slain was their sovereign, with his natural son, Alexander, Archbishop of St. Andrews, who had the learned Erasmus for his tutor; also two other Scotch prelates, four abbots, twelve Earls, seventeen lords, a great number of knights and gentlemen, and about eight thousand, or as some say, twelve thousand common men. According to Sir John Froisart, K. James fell near Brankston, where he was found the next day by Lord Dacres.
On the highest part of Flodden-hill, near it, is a natural rock, called the King's chair, from which he had a good view of his own, and of the English army, and of the country round him.
In the time of the battle the thieves of Tynedale and Tiviotdale were not idle. They rifled the English tents, and took away many horses, and other things.
From v2 of 'The natural history and antiquities of Northumberland' by John Wallis (1769). I love the way the mere 8 (12) thousand get bottom billing on the list of the dead.
History of the Berwickshire Naturalists' Club, volume 9 (1879-81) - has a list of "The named Stones of Northumberland; being a list of huge stones, single and in groups, in situ and detached, to which local names have been given in the County." by G. A. Lebour.
'A cup-marked stone in the Roman town of Corstopitum' - a short article by R H Walton in the 1962 edition of the History of the Berwickshire Naturalists' Club.
"Only the other day, gang after gang of Irish labourers was dismissed rather than agree to put an air-port runway across some thorn trees which they considered to be free from interference - even in the cause of "Progress." Perhaps the British workmen thought the same thing, in 200AD."