The Later Records relating to North Westmorland by John F. Curwen (1932) on British History Online.
Cumbria County History Trust has published a "Jubilee Digest" for the township of Dufton.
There is also a short history on the Dufton Village site.
Magna Britannica et Hibernia.Volume 6: Westmorland by Thomas Cox 45 pages, printed in 1731. Transcription by Sarah Reveley, Joan Fisher and Lisl Schoenwal.:
"Dufton, the Lordship of John Lord Graystoke, who having no Issue of his Own, and his Brothers and Uncles being dead without Issue Male, settled this and divers other Estates upon his Nephew Ralph, the Son of William Fitz-Ralph, Lord of Grimthorpe in Yorkshire and Joan, his Aunt, and dying 34 Edward I. left them to the said Ralph. He was summoned to Parliament by the Name of Ralph FitzWilliam, and dying 9 Edw. III. Left this Lordship, and his other Lands to his Son Robert, who outlived him but one Year, yet left a Son Ralph eighteen Years old, Heir of his Estates. Elizabeth his Wife survived him, and had for her Dowry an Assignation of this Lordship, and several others. The aforesaid Ralph being come to Age assumed the Name of Graystoke, and was summoned to Parliament under that Title. He was poisoned at Gatsheved as he was at Breakfast, and left his Estates to his Son and Heir William Lord Graystoke. He was summoned to Parliament from 22 to 31 Edw. IIII. Dying 32 Edw. III. Was found among other Estates to be possessed of this Lordship, which he left to his Son Ralph Lord Greystoke, and his Heirs, some of whom it seems alienated it, for we find Roger Lord Clifford 4th dying possessed of it 13 Rich. II. And leaving it to his Son and Heir Thomas."
According to Nicolson & Burn (1777): Duff was anciently a name in Scotland, and perhaps also in England. Macduff is a name well known; which means the son of Duff. And it is not improbable that Dufton (Duff's-town) might be so called from some person of that name.
More likely, according to Baron von Hymir de Dufton, the name 'Dufton' is derived from the mid-Saxon Dufa'-ton, = 'Place of Doves',
Earthwork fortifications stand on nearby Castle Hill, but recorded history begins after the Norman conquest when the manor was held by the Greystoke family.
The most famous son of Dufton was John Boste born in 1543 who was martyred in 1594 and canonised in 1970.