It is situated towards the head of the valley of the River Cocker and is surrounded by fells, notably the High Stile range to the south west, Robinson to the north-east, Fleetwith Pike and Haystacks to the south-east and Grasmoor to the north-west.

From his hidden stronghold at Buttermere, it is said that Jarl Buthar conducted a campaign of running resistance against the Norman invaders, from the time of William the Conqueror's Harrying of the North in 1069 right up until the early 12th century.

It is claimed that the Cumbrians fought a guerrilla war against the Normans for almost half a century, attacking supply wagons, ambushing patrols and inflicting great losses upon them in terms of money, material and men.

He is apparently mentioned in 12th-century Norman documents, but much of his story appears to be based on local legend and archaeology, later enhanced by Nicholas Size's popular dramatised history (see below).

Ferguson, "Ragnar's dale") between the Normans and the Anglo-Scandinavian Cumbrians led by the Jarl is the subject of a dramatised history by Nicholas Size, called The Secret Valley: The Real Romance of Unconquered Lakeland, published in 1930.