I suspect the name Isaac was given to him in part because his mother's name was Sarah.  Isaac in
 the Bible was the first and only son of Abraham by Sarah, both of whom were old, and Sarah well
 past childbearing age.  This is one of a few miraculous births in the Bible.

 He was christened again on Dec 3, two days before his mother was buried.  I am assuming she died
 in childbirth, or shortly after.
 When he and Catherine were married, he is listed as from the parish of Crassthorn, which is probably
 Crathorne Parish, north of Leake and west of Stokesley.

 Both Isaac and Catherine were born out of wedlock.

 In 1801, Isaac is listed in Loftus. his household included 2 males between 15 and 60, and 6 females
 (or others incapable of removing themselves). Isaac would have been 64 and Catherine 62.  Isaac Jr.
 would have been 21, and John 19, so they may be the 2. Aside from Catharine, and possibly Isaac Sr.,
 the 6 may have included Mary, who would have been 15, and possible younger daughters. There are
 marriages for Jane Swales and Catherine Swales nearby after 1801, but they would have been rather old.
 Ann may have married in Skelton in 1801, before the accounting.