Hello again Rob,
I have John Millership's (born 1865) parents as Richard Millership and Eliza Plant. There are 2 John Millerships one born in 1865 and one born in 1866. I am sure that the John Millership born 1865 is the one who married Rebecca Roberts.
I also thought that tracing the Millerships would be a simple task, but there may be different spellings of the surname millership.
Best Regards Mark.