20 Dollars Commonwealth of Australia

Australia's 1966 decimal changeover was one of the most compressed currency conversions attempted by any developed economy — the government gave the public just over two years of preparation before pound sterling notes ceased to be legal tender. This $20 note entered circulation on 14 February 1966, the day Australia switched, and the denomination itself was deliberately set at the equivalent of the old £10 to ease public mental arithmetic during the transition.

Four signature combinations exist across the series, reflecting turnover at the Reserve Bank governorship and the secretaryship of the Treasury — the Phillips/Wheeler pairing being the latest and consequently the most common. Coombs/Wilson, from the first year of issue, attracts the strongest collector premium.