The son of John Wallace or Wallis of Croglin, Cumberland, he was born at Castlenook, a farmhouse inside the ramparts of the Roman fort of Whitley Castle, South Tindale, in the parish of Kirkhaugh, Northumberland, in 1714.
Wallis, had to leave, and was taken into the family of his college friend Edward Wilson, vicar of Haltwhistle.
[1] In 1775 Wallis acted as temporary curate at St Andrew's Church, Haughton-le-Skerne, and in the same year was appointed to Billingham, near Stockton-on-Tees, where he remained till midsummer 1792, when illness obliged him to resign.
The Natural History and Antiquities of Northumberland, and so much of the County of Durham as lies between the Rivers Tyne and Tweed, commonly called North Bishoprick (London, 1769, 2 vols.)
[1] Some of Wallis's letters to the antiquary George Allan were printed in John Nichols's Literary Anecdotes (viii.