England therefore remained 10 days behind the New Style Calendar.
By 1752 England was some 11 days behind other European countries.
In publications you may see this written as January 1750/51, the year as it was known at the time / the year as we know it now.
In 1582 Pope Gregory XIII had reformed the calendar, then in use, known as the Julian Calendar (named after Julius Caesar).
The Julian Calendar did not correspond exactly to the solar year.
For further information about measurement see Colin Chapman, ‘How heavy, how much and how long?
: weights, money and other measures used by our ancestors’ (Lochin,1995).
Watch out for documents written in the reign of Charles II.