I've found some additional information on Robert (the elder) and Martha. According to the Birstall Marriage abstracts, Robert Rayner married Martha Wilson on 18 March 1811. If Robert was indeed baptized in 1790, this would make him 21 years of age at time of his marriage.
This also explains the name of their grandson, William Wilson Rayner. We've long wondered where the Wilson name came from, so it would appear that he was named for his paternal Grandmother's family.
I've also found out that Peace Hemingway, William Wilson's maternal Grandmother, is buried in the churchyard at St. Michael & All Angels in Thornhill, Dewsbury. His aunt, Mary Rayner (wife of Daniel) is also buried there. Peace died 15 December 1867 at age 62. Mary died 3 September 1870 at age 40.
Paul