Ah, my new favorite family has now upped their game -- with an ancestor listed as a Concubine!!!
This is in St Helier, Jersey, Channel Islands - 1871 Census.
Prudence Brint is a daughter of Elizabeth "Betty" Fursland and Stephen Brint. If you're following my blog, then you'll know that the Fursland family is from Devon, and three Sisters and a brother ended up in Jersey. Betty married Stephen in 1842, and their daughter Prudence ends up living with a man 14 years her senior in 1871. He is listed as unmarried, and she is listed as Concubine. They have 2 children already, and go on to marry in 1872, and have 6 more children.
I wonder whether the Census Enumerator knew that they weren't married, and listed her this way? They must have been openly living together with their children. And when they marry, he is not listed as a widower -- so that doesn't account for it.
A mystery I will probably never solve.....