alanagr ... following our meeting ... I have found a reference to Nancy, wife of Samuel Cameron, who died 4/12/1885, and mother to Betty Cameron, who was born c.1854. This is close to Rosey Cameron, born c.1847.
Cameron Erected by Samuel Cameron in memory of his daughter Betty, who died 04 Sep 1876 aged 22. Also his wife Nancy who died 04 Dec 1885 aged 71.
St John's Church of Ireland, Islandmagee, graveyard.