Bruce,

Thanks for your help. You are right - Catherine E Boyde is in the 1871 census with her family (no 1). By the time of the 1881 census, she should be 22/23 but she isn't with her family. She married William Thomas Cowle (later Cowell) in Jun 1882 and gave her address as the White House, Balladoole, Lezayre. I had hoped that someone on this site would know where that was.
I haven't yet worked out the connection between Catherine C Howland and my family. I have found that she was the daughter of William Howland, a fisherman, and Sarah Cubbon. She was born on 10 Oct 1878 in Peel, which doesn't quite match with her age in the 1881 census. That census shows William and Sarah living in Peel with five children under 10 - so it is little wonder that they farmed out the little one! If my research is right, Sarah Cubbon may be related to the Boydes, but I have yet to prove the connection. By 1891, Catherine Howland was 14 and living at Ram 1/15 as a servant girl. It later occurred to me that she might be the illegitimate daughter of the eldest daughter, Elizabeth, masquerading as someone else, but it does not look like it.

Thanks for your help,

James