This attractive 10" plate dates c 1850. It is in excellent condition, with no chips, no crazing, and no repairs. There is a tiny firing crack (done in the making) on the foot rim. Despite that, the plate rings when tapped.
"Floral with Key Border" is an assigned name of the Mason's Collector's Club for this pattern, and their code is EF137a.
The black printed mark on the back reads only: Masons Patent Ironstone China with the angular crown and drape.