The Huguenots were French Protestants who left the country to avoid religious persecution after the Revocation of the Edict of Nantes in 1685. Richard's father was born about a century later, so he wasn't a Huguenot!
Unless Syndonia Bailey married 2 men with the same unusual surname (brothers?), I think it's likely that his father was Robert, as suggested by the IGI marriage record, and that whoever registered Richard's death got the name wrong - my g-grandmother's death certificate, for example, has the wrong name for her deceased husband.
Other possibility: his full name was Robert Emile or Emile Robert...
The IGI has a birth records for:
John Dumelow, son of Robert Dumelow and "Sindania", chr. Castle Donnington, Leics in Feb 1805 (no exact date).
Ann Dumelow, dau of Robert and "Sindena", chr Castle Donnington 22 Mar 1804
Quite a few other Dumelows (and other spellings!) at Castle Donnington, so it might be worth ordering the microfilms if you have a LDS centre not far from where you live.
Maybe the Dumelows originally came to Castle Donnington as French refugees, and family oral history "compacted" the story a bit?
Nothing very concrete here, I'm afraid, but keep digging!
Rambler