Hello Adrienne,

On the Familysearch website the closest Baptism to 1865 is –

Name Margaret Cubbon
Christening Date17 Jun 1866
Christening PlaceMALEW,ISLE OF MAN,ENGLAND
Father's Name
Mother's Name Jane Cubbon

If this is Margaret’s son (below) then you might have more luck tracing his Spouse’s surname.
Or looking for a WILL of his father – to see if he is mentioned in it.

NameJohn Walter Cubbon
Event TypeMarriage
Event Date26 Jul 1921
Event PlaceDouglas(St George's), Isle of Man
GenderMale
Marital StatusSingle
Father's NameFrederick Cubbon
Mother's Name
Spouse's NameIrene Mcginley
Spouse's Marital StatusSingle
Spouse's Father's NameFrank Mcginley
Spouse's Mother's Name
Digital Folder Number004499427

Averil