NOTES on the BRITISH CALENDAR BEFORE 1753
...which this routine acts on, subject to the following:-
PLEASE NOTE that before 1753, the British year started on March 25th, NOT January 1st.
If you enter a year pre-1753 (with date Jan 1st-25th March), enter the year as it would become on the subsequent March 25th.
(i.e. pretend that the year started 1st January) ALSO, in 1752 the dates September 3rd to 13th were dropped from that year's calendar in order
to correct the calendar from its accumulated errors.