Credit to Wikipedia: https://en.wikipedia.org/wiki/Threepence_(British_coin
Early 20th century
The currency threepence was issued for each of the nine years of the reign of King Edward VII from 1902. The reverse design remained the same, while the obverse showed the right-facing effigy of the king, with the inscription EDWARDVS VII D G BRITT OMN REX F D IND IMP.
The reign of King George V (1910–1936) features several changes to the threepence denomination. As with all British silver coins, the silver content was reduced from sterling (0.925) silver to 50% silver, 40% copper, 10% nickel in 1920, 50% silver, 50% copper in 1922, and 50% silver, 40% copper, 5% nickel, 5% zinc in 1927, while the design of the reverse of the circulating threepence (but not the maundy threepence) was completely changed in 1927 to three oak sprigs with three acorns and a "G" in the centre, and the inscription THREE PENCE date. The inscription on the obverse throughout the reign was GEORGIVS V D G BRITT OMN REX F D IND IMP.
The threepences of King Edward VIII were all patterns awaiting royal approval at the time of the abdication in December 1936. The silver threepence had another completely new reverse – three interlinked rings of Saint Edmund, with the inscription FID DEF IND IMP 1937 THREE PENCE, while the obverse shows a left-facing effigy of the king with the inscription EDWARDVS VIII D G BR OMN REX and a very small silver engravement.