The 1871 census gives John's age as 62 and Esther's as 70.
The IGI has no John Gawne christened in Santon with corresponding dates. I thoght that possibly he was born in a bordering parish
Marown, Braddan or Malew. The closest I came is a John Gawn christened in Braddan on November 12 1809, son of John Freer and Elizabet Gawne.
There is an Esther McNeil on the IGI christened on March 7 1802 at St. Mark Malew.
Her parents are shown as Thomas McNeil and Hannah Harn.
However these entries - there are two- were not transcribed from parish records but were submitted by a LDS church member. Harn is not a Manx name that I have come across and looks like a mistranscription.
Bruce