No, I am not about to hit the town with a girlfriend and a couple of lads. The concept of double, or dual, dating in record keeping was introduced to deal with the period (different years in different countries) when scientists concluded that the calendar was out of synch with the lunar year and the change was made from Julian dating to Gregorian dating. The change involved disposing of 11 days and moving the start of the year from March to January thus causing the months to be renumbered. I have often wondered why September, October, November and December (7ber, 8ber, 9ber, 10ber) had numbers inconsistent with their place in the calendar year. Now I understand that this was based on their position calculated in the Julian calendar with March as month 1. One effect of the change in England was that people went to their beddy byes on Wednesday 2 Sep 1752 and woke up the next morning on Thursday 14 Sep 1752. Needless to say there were soon riotous mobs screaming to have the missing 11 days of their lives back. For the genealogist it creates some interesting challenges. Records in the mid 1700s can show both OS (old style) and NS (new style dates). This explains some of the problems I had interpreting the Elsdon records I read at Easter so I am going to have to QA my findings. I also need to look more closely into whether I have any errors in my genealogy database because England and Scotland implemented the change at different times. I learn something new every day that I work on this research. If you want to learn more about this calendar change yourself take a look at Chesterfield’s Act.