The Julian calendar was introduced in 45BC by Julius Caesar.  Based on a solar year, it had twelve months, but a miscalculation of 11 minutes resulted in a leap year formula that overcompensated to the extent that every 128 years, a whole day was added.  By the 16^th century, astronomical events such as the equinoxes and solstices were falling ten days early, and since the timing of Easter was linked to the vernal equinox, it was increasingly becoming removed from its proper season.  To overcome these problems, in 1582 Pope Gregory XIII introduced the ‘Gregorian’ or ‘New Style’ Calendar.  Not all countries followed suit immediately.  In fact it wasn’t until 1927 when Turkey finally made the switch, that everyone was on board.  However, since the change-over involved cutting ten days from one month in the first year of adoption of the new calendar, countries that didn’t change over were ten days ahead of those that did.

It was in 1751-52, following the Calendar (New Style) Act of 1750, that the UK (and British dominions) adopted the Gregorian calendar.  By this time the UK calendar was eleven days out of sync with the astronomical events and seasons, and these days were removed in one fell swoop in September 1752.  In that year, September 2^nd was followed by September 14^th.  Many of our ancestors were distinctly unhappy about the loss of eleven days.  There was a genuine fear that their lives would be shortened by that number of days.  They were also concerned at the interference with the Church calendar, particularly with the moving of Easter, and on top of all that they objected to the imposition of what they viewed as the ‘popish’ calendar.  This may or may not have resulted in the ‘English Calendar Riots’ of 1752.  Many historians today view them as a sort of Georgian urban myth.

However, the removal of the eleven days was not the only important change to flow from the Act of 1750, and it is this other aspect that impacts upon us as genealogists.  Prior to 1752 the English year began on 25^th March.  This was Lady Day, one of the four Quarter Days, the others being Midsummers Day (24^th June), Michaelmas Day (29^th September) and Christmas Day (25^th December).  I first learned of Lady Day while studying Tess of the d’Urbervilles for English Literature A-level – it was the day tenancies changed and rents were due; and Tess, with her recently widowed mother and siblings, were evicted from their cottage.

Before 1752, then, December 31^st and the next day, January 1^st were in the same year.  The year continued until March 24^th after which, on March 25^th, the new year would begin.
The 1750 Act provided for a changeover involving the following series of steps:

• 31^st December 1750 was followed (as usual) by 1^st January 1750, and 24^th March 1750 was followed by 25^th March 1751.
• 1751 was a short year, running from 25^th March to 31^st December, then December 31^st 1751 was followed by January 1^st 1752.
• Finally, with the removal of the eleven days in September 1752, September 2^nd of that year was followed by September 14^th.

For us as genealogists it’s the period between 1^st January and 31^st March in each year before 1752 that can confuse.  If you look at any parish register before this time you’ll see for yourself that the recording year did indeed start on 25^th March and end on the 24^th.  So if your ancestors married on 1^st April 1632 and their first child was born on 1^st February 1632, that child was born ten months after the marriage, not two months before it!  You might also have come across unlikely coincidences in record sets such as the birth of Elizabeth to parents James and Mary on 15^th January 1732, and another Elizabeth to the same parents on 15^th January 1733.  What really happened is that one transcriber amended the date to the Gregorian calendar and the other didn’t.

Historians and genealogists can get around this confusion by using a technique called ‘double dating’.  Any date after 25^th March is recorded as usual (e.g. 1^st April 1632).  However, any date from 1^st January to 24^th March is recorded in a way that recognises its position both within the Julian and the Gregorian calendars: e.g. 1^st February 1632-33, or 1^st February 1632/3.  If you’ve already got your research back to these earlier parish registers, you may decide to use this system.  However!!!! the online trees find it difficult to cope with.  After asking you repeatedly if you’re sure this date is correct, it will accept it but only show the earlier of the two years in the person’s profile.  Be strong!  It’s your tree!  😀

One final aside….
There’s another important side-effect of these changes, and one that remains with us today.  Formerly, being the start of the year as well as the first Quarter Day on which rents were due, Lady Day was also the start of the English tax year.  However, with the loss of the eleven days in September 1752, it was deemed appropriate to delay the collection of taxes to April 5^th, thereby avoiding the loss of eleven days of tax revenue. That’s why, following another tweak to the calendar in 1800, the UK tax year starts on the surprising date of 6^th April.  And after a quick revision online, I now see that the date in Tess of the d’Urbevilles is ‘Old Lady Day’: 6^th April.  Is this an indication that a hundred years after the event, rural England hadn’t fully embraced the new calendar, or did landlords move the day rents were due to coincide with the new tax year…?