I have another theory.
1853 - Sarah Ann HOLE birth registered Exeter AMJ 5b 92
1853 - Richard Thomas FILDEW birth registered E. Stonehouse OND 5b 270
1861 Census - cannot find
1871 Census
Coombe Street
St Mary Major, Exeter
RG10/2064/22/33
Francis HOLE, Head, 41, Fish Labourer, born Woodbury
Eliza HOLE, Wife, 40, born Bishops Teignton
Walter HOLE, Son, 21, born Exeter; Trinity
Sarah A HOLE, Daughter, 19, born Exeter, St Mary Major
Francis HOLE, Son, 11, born Exeter, St Mary Major
Thomas HOLE, Son, 8, born Exeter, St Mary Major
Eliza HOLE, Daughter, 6, born Exeter, St Mary Major
William HOLE, Son, 2, born Exeter, St Mary Major
Just a few roads away;
1871 Census
Under the Wall
St Mary Steps, Exeter
RG10/2066/22/37
Henry FILDEW, Head, 47, Honiton
Ann FILDEW, Wife, 45, North Lew
Ellen FILDEW, Daughter, 15, Stonehouse
Charles FILDEW, Son, 12, Stonehouse
Louisa FILDEW, Daughter, 10, Stonehouse
Edwin FILDEW, Son, 8, Stonehouse
Fredrick FILDEW, Son, 6, Plymouth
Thomas FILDEW, Son, 17, Stonehouse
1872 - Thomas FILDEW marries Sarah HALL *possible mistranscription*
1874 - Richard Thomas P FILDEW dies ages 21.
Sept 1878 - William Samuel FILDEW born
OND 1878 - Sarah FILDEW marries William Samuel FILDEW
1879 - William Samuel TESTER dies aged 30.
1881 Census (as you found before)
40 Preston St
St Mary Major, Exeter
Sarah TESTER, Head, Widower, 29, Laundress, born Exeter
Wm. TESTER, Son, 3, Exeter
Unfortunately it is all a bit tenuous and I think a few more certificates are needed to see once and for all.