1911 Encyclopædia Britannica/Lady Day
LADY DAY, originally the name for all the days in the church calendar marking any event in the Virgin Mary’s life, but now restricted to the feast of the Annunciation, held on the 25th of March in each year. Lady Day was in medieval and later times the beginning of the legal year in England. In 1752 this was altered to the 1st of January, but the 25th of March remains one of the Quarter Days; though in some parts old Lady Day, on the 6th of April, is still the date for rent paying. See Annunciation.