This article about how historians’ perceptions of the ‘legendary figure’ have changed over recent times is behind a pay wall: I am trying to access it. Meanwhile…

Forty years ago both scholarly histories and historical novels had a common view of Arthur: as a historical warrior, whose leadership enabled his people, the native inhabitants of post-Roman Britain, to halt the advancing tide of Anglo-Saxon conquest for about half a century. Nobody was exactly sure when this was, because it had been in the obscure period between 410 and 550, which has left almost no contemporary documents. Nonetheless, there was general agreement that Arthur had flourished somewhere in that time and had been the greatest British personality in it, establishing a fame which laid the basis for the later, more romantic and fantastic, medieval Arthurian legend.

This happy consensus had mostly been produced by the new discipline of archaeology, which had excavated some of the main sites associated with Arthur in that later and fully-developed legend, such as his birthplace at Tintagel and Cadbury Castle in Somerset, which local tradition held had been his court of Camelot. In each case, amid great publicity, spectacular remains had been found of occupation by wealthy people at just the right period. For many, this was enough to establish beyond reasonable doubt that the legend was rooted in historical truth and books such as Geoffrey Ashe’s The Quest for Arthur’s Britain  and Leslie Alcock’s Arthur’s Britain carried this message to a wide readership. It was taken up by historians, who now felt encouraged to reconstruct a story for the years around 500 by combining the meagre early medieval sources with a wealth of much more dubious data from later periods; this approach was epitomised by John Morris’s fat, exciting book, The Age of Arthur . The interest stirred up by scholars resulted in a flood of historical fiction in the 1960s and 1970s. Most was produced by Englishmen, though Englishwomen such as Rosemary Sutcliff and Mary Stewart were among the most prominent authors. All treated Arthur as a historical character in a post-Roman setting, with realistic British landscapes and careful use of historical and archaeological data.

Source: Signposts: King Arthur | History Today.