Dm of an unnamed mare by Darcy's Yellow Turk through which the maternal line of the family continues

The term "royal mare" was a name used to describe a number of mares in the Sedbury stud of father and son James Darcy which were, like this mare, known as a Sedbury Royal Mare, and sometimes to mares from the Royal Stud at Tutbury (broken up by Cromwell) or later at Hampton Court.

The appellation "royal" for at least some of these mares probably relates to the agreement in 1661 between James Darcy (the elder), the King's Master of the Horse, and Charles II for Darcy to supply the King with colts from mares of Darcy's "own breed".

Mitochondrial DNA has shown that Family 13 shares the same maternal line as Families 4 and 11. As there is no identifiable link between the families in historical records, the Sedbury Royal Mares which are the Foundation Mares of Families 11 and 13, and the Layton Barb Mare, Foundation Mare of Family 4, must all share a common maternal ancestor which predates the historical records.