The Act responsible for a widespread panic which occurred following the loss of 11 days. Europe had operated under the Julian Calendar introduced by Julius Caeser in 46 BC. The year was set at 365 days with an extra day introduced every fourth or leap year. However it was already known that the year was in fact a few minutes short of the 365.25 days set in the regulation. This resulted in the calendar gaining about three days in every four centuries when compared to the actual observed equinoxes. This was corrected by the Gregorian calendar introduced by Pope Gregory XIII in 1582. There was in fact a religious reason for its introduction as the date of Easter was set by the spring equinox. It was initially adopted by the Catholic countries of Europe, the Protestant and Orthodox maintained the Julian calendar. Over time most countries converted as it was causing all sorts of issues in trade and politics. The last to convert were Greece in 1923 followed by the Soviet Union in 1930.

The adjustments meant that although every year divisible by four was considered a leap year those divisible by 100 were not. They were however if they were divisible by 400, therefore 1800 and 1900 were not leap years but 2000 was. This changed the length of the year from 365 days 6 hours to 365 days 5 hours 49 minutes and 12 seconds. Britain adopted the calendar with this act passed in 1751 the following year 1752. First it was decreed that the New Year would begin on 1 January 1752, not March 25th as had been the case. Secondly it was decided that Wednesday 2 September 1752 would be followed by Thursday 14 September 1752. At the time many people complained about the lost 11 days and many worried that their lives were being shortened by that much. It was also seen as a Popish calendar.

The change also had tax implications as the new year used to begin on Lady’s Day March 25th. The change of calendar meant this was now 1 January. To maintain revenues, the tax year stayed where it was but was moved to the 5 April to account for the 11 ‘lost days’. One further change was made in 1800 when a further day was lost as it was not a leap year. From that day to this the start of the tax year in Britain has remained the 6 April. Overall a remarkable document in English history. Included with the Act are ‘The New Calendar, Tables and Rules, Mentioned, and Referred to, in the Act For Regulating the Commencement of the Year; and for the Correcting the Calendar now in Use’. ESTC 52459.