Per the 1851 census both Joseph and Margaret were born in the Isle of Man.
TJE IGI has a Joseph Kneale, son of William Kneale and Ann Fargher, christened in Lonan on October 18 1818.
They married in Lonan on June 16 1806, so they were probably born prior to 1786.
I did not any obvious match for this couple in any census