A George V 1920 Sydney mint gold sovereign has set a new world record for an Australian coin, at the second instalment of the Bentley Collection auction in London.
With just four known to exist, and one of those in a museum, the rarity of the stunning beauty pushed its price to £780,000 ($1.3m).
In doing so it surpassed the previous $600,589 record for one of the four coins, set at an auction in 2006, by 109.7%, or 13.1% pa.
The result is also believed to be a new world record for a British colonial coin, a legal tender British coin, as well as a British auction record for a 20th century coin.
"We are absolutely overjoyed with today's result, we hoped it would be a great day but it far exceeded all of our expectations," said Steve Hill, auction house Baldwin's British coin expert.
The auction also featured a South African George V 1929 Pretoria mint proof sovereign, which made £52,800 ($85,276) against a £15,000 valuation, while a South African single shaft 1892 gold Pond sold for £38,400 ($62,019), far surpassing its £25,000 high estimate.
The results are confirmation of the Bentley Collection as one of the finest sales of British and Commonwealth coins ever seen, with the series featuring at least one example of every sovereign date issued in the UK between 1816 and 1971.
The first auction, which took place in May, included a Queen Victoria 1887 sovereign, which sold for £28,000 ($45,226).
The last of the three auctions, scheduled for May 2013, will include one of the most sought-after of all British coins - an 1819 gold sovereign. Described as "excessively rare", only six examples are known to exist.
View our collection of British and Italian coins for sale here.