Update: Rev. Chris at St Peter's discovered an index of monumental inscriptions and gravestones and found that John and Eleanor were indeed buried together with their daughter Margaret and son David. He took photos too.
John died 28/1/1879; Eleanor died 11/12/1878, David died 17/4/1857 and Margaret died 7/2/1834.
If anyone else is researching our family, please get in touch.