Interesting comments re Bolehill (Lawrencefield) and Millstone Edge.
I'm fairly sure that Millstone Edge is a misnomer, and that it was from these much larger quarries that Derwent/Howden reserviours were built, and that the millstones mainly came from Bolehills (the much smaller quarries with all the millstones stacked up underneath!)
(that being said, I'm sure millstones were probably quarried at 'Millstone' before the much larger dam building project came along and upscaled the quarrying there)