The inscription on the stone in St Thomas’s Chapel (the Chancel) states that Jane Stuart died on 26th of February 1741/2. Jane Prouting’s gravestone nearby gives her date of death as 7th January 1742/3.  In Portsmouth Cathedral there are four memorial stones with dates that contain fractions – ‘the two Janes’ and two others. They highlight the changeover from the Julian Calendar (adopted by Julius Caesar in BC 46) to the Gregorian Calendar (sponsored by Pope Gregory XIII in 1582).  Elizabeth I, however, decided that we were happy to retain our ‘own’ Julian Calendar.

For events happening in January, February or March, the year 1741/2 is interpreted as 1741 or 1742. Likewise, 1742/3 means occurring in 1742 or 1743. Which year is chosen depends on whether the Julian calendar or the Gregorian calendar is being used. In England, the two systems were used in parallel for 170 years, until in 1752 Lord Chesterfield’s Act of Parliament announced the formal adoption of the Gregorian Calendar in England to put an end to any confusion.

A simplified explanation is that in 1582, when Pope Gregory XIII suggested his calendar as a replacement for the Julian calendar, two changes were decided. First, 11 days had to be lost. To bring us into line in 1752, the government decided that September 2nd would be followed by September 14th. In 1752, September 3rd-13th ceased to exist! This caused riots in some places with people demanding back their ‘stolen’ 11 days - especially hard if you lost your birthday: no songs, no cake, no presents!

Second, New Year’s Day was brought forward to 1st January from March 25th (Scotland introduced this in 1600). For quite some time before and after 1752, both Calendars were in use, and some documents and monuments from that time had ‘OS’ (Old Style) after the date to indicate that the date is according to the Julian Calendar; others had ‘NS’ (New Style) indicating that they were using the Gregorian Calendar. When the beginning of the year changed from 25th March back to 1st January, some people were not sure which year to record. If you were hatched, matched or despatched in February, it was 1752 according to the Old Style (New Year’s Day 1753 being ahead of you on March 25th) but 1753 according to the New Style (New Year’s Day having been on 1st January).

To overcome this period of uncertainty, some documents, monuments and gravestones were written or inscribed with both years, for dates between 1st January and 24th March. The fractions on memorial stones were a way of highlighting the confusion caused by using two calendars.