11 Numbers and dates
11.7 Regnal years
Regnal years are marked by the successive anniversaries of a sovereign’s accession to the throne. Consequently they do not coincide with calendar years, which up to 1751 in England and America—though not in Scotland—began legally on 25 March. All Acts of Parliament before 1963 were numbered serially within each parliamentary session, which itself was described by the regnal year or years of the sovereign during which it was held. Regnal years were also used to date other official edicts, such as those of universities.
Regnal years are expressed as an abbreviated form of the monarch’s name followed by a numeral. The abbreviations of monarchs’ names in regnal-year references are as follows:
P. & M. (Philip and Mary)
Wm. & Mar. (William and Mary)
Vic. or Vict. (Victoria)
The names of John, Anne, Jane, and Mary are not abbreviated. See