Calendar (New Style) Act 1750
New Year's Day (Lady Day) in England, Wales, Ireland, and some of the future United States and Canada from 1155 through 1751, until the Calendar (New Style) Act 1750 moved it to 1 January and adopted the Gregorian calendar. (The year 1751 began on 25 March; the year 1752 began on 1 January.)
It was also New Years Day in Scotland until (and including) 25 March 1599; 1600 in Scotland began in 1 January – see Calendar (New Style) Act 1750#Scotland.