Okay, Stephen.
Michael Joyner left a will and Dorset Record Office have a holograph copy. Death duties were paid on this and the 1817 index on Find My Past shows that the executor was Geo Joyner, who I assume was Michael's youngest son, and your ancestor?
This link, which you have probably already found, seems to have a passing reference to Michael Joyner:
http://www.communigate.co.uk/dorset/...et/page3.phtml
I can't find a marriage of Henry Joyner to Mary. This doesn't completely surprise me. A lot of the Dorset records don't seem to survive and Corfe Mullen is close to, if not actually on the coast, so people could arrive from other counties.