AKA Dam of HARTLEY'S BLIND HORSE, Makeless Mare
The fourth earliest mare in the lineage of Family 13
Dam of an unnamed mare by Soreheels through which branches 13-a, 13-b, 13-c and 13-e of the family descend; and of Gipsy (by King William's Black Barb) through which branch 13-d descends.
Described in Pick's Turf Register as "the highest and best bred mare in England".
The GSB says that Darcy's Royal Mare [also known as Kit [Christopher] Darcy's Royal Mare] is the dam of Milbanke's Black Mare, but pedigree certificates for the horse Creeper (1716) given by James Darcy, the younger, state Milbanke's Black Mare is a half sister to Darcy's Royal Mare, not her daughter, both being out of Grey Royal.
A highly influential broodmare, she is dam of the successful stallion Hartley's Blind Horse; of Soreheels Mare (dam of useful racehorse Danby Cade and 3rd dam of the great racehorse and sire Highflyer, Champion Sire 13 times); and of Gipsy (grandam of the useful racehorses Diana and Charming Molly).
https://www.bloodlines.net/TB/Families/Family13.htm