From 'Exploration of a second mound near Stonyhurst' by the Rev. J R Luck:
Many legends find currency among the country people concerning it. According to one, a powerful chieftain, robed and seated in a chair, was entombed within; another told of a casket of gold lying beneath; while a third relates that Oliver Cromwell, or at least some of his troopers were buried in it. However, the most generally received tradition is that the followers of Wada, slain in the battle between that rebellious chief and King Eardwulf, were buried here, while those slain of the king's army were buried in the other mound. The victims of the routed army being more numerous than those of the victorious, of course accounts for the greater size of this mound.
Transactions of the Lancashire and Cheshire Antiquarian Society, v13 (1896).
The Rev dug into the mound and concluded it was a natural feature left behind by glaciers, but the modern SMR is more forgiving.
The date of this site is debatable - it is quite possible, due to it's proximity to the other barrow at Winckley Lowes, that this is a Bronze Age site. However some have claimed the mound to have been built after the battle of Billington in 789ce.
Simeon of Durham gives an account of that battle:
"A confederacy was made of the murderers of King Aethelred; Wada, chief in that conspiracy, with his force went against Eardwulf, in a place called by the English Billangahoh (Billington), near Walalege (Whalley), and on either side many were slain; Wada, the chief, with his men, was put to flight, and King Eardwulf regally achieved victory over his enemies."
The Anglo-Saxon chronicles of that year state:
"In this year in Spring, on 2nd April, there was a great battle at Whalley in Northumbria, and there was slain Alric, son of Heardberht, and many others with him."