Knuckey is an old Cornish name which later morphed to Newkey.
Verdon and George Newkey added the name Burden to theirs as instructed by the will of their stepfather who died 1826. I am related to the Newkey-Burden line and we are still from the West Country. I have a George Philip Newkey (1787) and know of his father Philip Newkey but no birth date. I don't know when the name morphed from Knuckey but it was probably when writing and reading were uncommon.