The George V sovereign series was struck from 1911 to 1931 with the design changing from 1928 to 1929 with the two types being known as the Large Head and Small Head design respectively.
The issue was struck in Australia at the Sydney, Melbourne and Perth mints up to 1926 and only the Melbourne and Perth mints thereafter. The mint of manufacture can be determined by the letter S, M or P on the exergue above the date denoting Sydney, Melbourne and Perth respectively.
Most of the early half of the series, up to 1918 are reasonably easy to acquire in lower mint state grades though some years, particularly those from the Perth mint become very difficult to acquire at the MS64 level and command strong prices whenever they do come to the market. The 1918-S is the easiest date for the very high grade range making it an excellent candidate for a type set.
The latter half is home to some very difficult issues, the most famed of which being the 1920 Sydney which is known by about 4-7 examples plus one specimen, one of only two Australian coins to sell above A$1M.