Cary used Greenwich as the origin for the prime meridian on many of his New County maps, however a number are based on “London”. Mostly the London origin is west of Greenwich; the example shows various New County maps from 1° East to 6° West. Green meridians are those based on Greenwich; red meridians are based on “London”. A general westward increase in error is seen; Somerset is problematic in that the London origin plots to the east. The Middlesex County map gives a good indication of the location of the “London” origin.