I had no idea until I read a leaflet from the Friends House Library today that there was a discrepancy in dates between Scotland and England. Their helpful PDF leaflet on Quaker dates also has a section on the change from the Julian calendar, where the first day of the year was March 25 and the Gregorian, where the first day of the year changed to January 1.
This means that 1752 was a “short” year, from March 25 to December 31. You will also sometimes see people refer to the fact that the way of dating changed, by putting 1 February, 1749/50. The explanation in the PDF leaflet is very good. I knew that twelve days had to be lost from the calendar to bring Julian and Gregorian into synchronicity, but I did not realize Scotland adopted the Gregorian calendar in 1600. That must have made correspondence between England and Scotland rather problematical!
The leaflet is very good in the explanation which it gives for Quaker months and numbering, and is to be highly recommended if you have Quaker ancestors. As is the Library of Friends House, which has amazing resources for any Quaker family historian.