Change of Year - update
Regarding the question submitted on years that change on Mar 25, i.e., in the U.K. and the colonies, I think the given answer missed the question being asked. Prior to 1752 the new year began on Mar 25, Lady Day. Called Lady Day after Our Lady, the mother of Jesus. Since Jesus was born on Dec 25, He was obviously conceived on Mar 25, thus the beginning of the new year on that date.
The answer to the question depends, of course, on the project instructions. However, absent any other project information, the year to be indexed is the year written on the record, and should not to be modernized. After 1752 the U.K. and colonies adopted the Gregorian calendar, with new years day being Jan 1.
Sometimes this is answered in Project Instructions. If not then we follow this rule:
"For events except births that include a date range, such as “between February 2 and March 9, 1937,” type the most recent or latest date in the range. For this example, type the month as Mar, the day as 9, and the year as 1937. "