Note to CRAIG SHELDON - read the MI again, it says lived WITH husband 47 years, ie 47 years from date of marriage.
Ancestry.idiot gives what?
"NOTE FROM CRAIG SHELDON: Mary Roberts nee Barne's age at death of 47 years (given on the ledger stone in St. Mary's of Willesden; see below) conflicts with the recorded dates of birth of her children (cf. Love's Mirror). Ancestry.com trees give a more likely date of birth of 1555.