This showed where the Historical Year 1734 started even though the Civil Year 1733 continued until 24th March.An individual date would be shown as, for example, 3rd March 1733/4 so we are left in no doubt that the date intended was in March of the Civil Year 1733 and the Historical Year 1734, that is, the month before April 1734.
England could not help being influenced by the Gregorian calendar.An oblique stroke is by far the most usual indicator, but sometimes the alternative final figures of the year are written above and below a horizontal line, as in a fraction (see photograph). The phrase Old Style, abbreviated as OS, was also used as when Lord Chesterfield wrote to his son in Rome on 8th January 1750/51 and used the form "January 8, O. 1750." Note that, whatever notation is used for the dual dating, it only has meaning in the period 1st January to 24th March each year (and of course for England and its colonies only before 1752).From 25th March to 31st December the Historical Year is the same as the Civil Year number so no special indication is necessary.So the ambiguities are not just a problem for historians looking back with hindsight; they were a contemporary problem for which contemporary solutions are evident.Before 1752 parish registers, in addition to a new year heading after 24th March showing, for example "1733", had another heading at the end of the following December indicating "1733/4".(There is another form of dual dating used by some historians, where a date is given in its original, Julian and Civil Year form , followed by a "mapping" of that date to its Gregorian and Historical Year equivalent, as in "10/22 January, 1705/6." This format is not recommended.