Prior to 1751 (when the calendar was reformed), the register year would go from Lady Day to Lady Day (25 March) so, for example 31 December 1740 would be followed by 1 January 1740 (actually 1741).

http://www.hungerfordvirtualmuseum.co.uk/index.php/13-archiv...

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Note added at 1 hr (2017-03-24 09:12:00 GMT)
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There are sometimes gaps in the registers because the priest or parish clerk didn't fill them
in at the time and forgot to record the event. Another complication with early registers is that
they didn't start a new year on January 1st. The new register year was taken from Lady Day
(25 March), so any entry from 1 January to 25 March will be in the register for the previous
year. This way of recording events was abandoned in 1752 when Britain adopted the
European calendar, which was 11 days shorter than the British one. This meant that the
calendar year in 1752 had the 3 September followed by the 14th! This was so the calendars
could be brought into line. The old British calendar was called the Julian calendar and the
new European calendar is called the Gregorian calendar- the one we use today.

http://www.yac-uk.org/userfiles/file/1429015253_Church_and_g...