With Decimal Day soon approaching, the British half crown was last struck for circulation with the date of 1967 and was demonetised in 1970 (p58, Norfolk, An Introduction to British Milled Coinage 1662-1971 Part VII Conclusion in Coin News, March 2025). The final half crowns were dated 1970 and were only struck for proof sets. Although the half crown obverse had not changed since 1962, two different obverses were used to strike the proof sets.
The two different obverses which Davies denotes as 2 and 3 can be differentiated by examining where the I in GRATIA points - on obverse 2 it points at a denticle and on obverse 3 it points between denticles. Davies reported obverse 2 as being unconfirmed for 1970-dated half crowns (p103, Davies, British Silver Coins Since 1816, 1982) but it has since been confirmed. The exact percentage of each variety is not known, but obverse 3 is believed to be much more common.
The reason for a new obverse die being introduced is not known: although it is tempting to say that all the London struck coins used obverse 2 and the Llantrisant coins used obverse 3, it is more likely is that obverse 2 was not found suitable for striking large numbers of proof coins - proofs had only ever been struck in comparatively small numbers up until 1970 - and a new and more durable design was needed to strike the bulk of the mintage.
With the onset of decimalisation, the British florin was struck with the frozen date of 1967 in the last few years of its life, with the final florins being dated 1970 and only being available in proof sets. Although the florin obverse had not changed since 1954, the striking of the proof sets saw two different obverses used.
The two different obverses which Davies denotes as 1 and 2 can be differentiated by examining where the E in DEI points - on obverse 1 it points between denticles and on obverse 2 it points at a denticle. Davies reported obverse 1 as being unconfirmed for 1970-dated florins (p105, Davies, British Silver Coins Since 1816, 1982) but it has since been confirmed. The exact proportions of each are not known but Gouby reports finding approximately five obverse 1 coins in approximately 80 proof sets (Gouby, http://michael-coins.co.uk/GBflorins3.htm).
The reason for a new obverse die being introduced is not known: although it is tempting to say that all the London struck coins used obverse 1 and the Llantrisant coins used obverse 2, the numbers do not agree - approximately 13.6% of coins were struck in London and approximately 6% of coins were struck with obverse 1. More likely is that obverse 1 was not found suitable for striking large numbers of proof coins - proofs had only ever been struck in tiny quantities until 1970 - and a new and more durable design was produced for the bulk of the mintage.
In 1935 the Royal Mint struck a crown to commemorate King George V's silver jubilee. Although the crown had stopped circulating in the United Kingdom in the early 1900s, 714,769 pieces, as well as 2,473 proofs were struck to celebrate the occasion. The reverse design was entirely new, although it featured the familiar motif of St George and the dragon, this time designed by Percy Metcalfe. The edge inscription was * DECUS ET TUTAMEN * ANNO REGNI XXV and it was incuse in the edge, except on some proofs where it was raised.
Besides the standard circulation-style pieces, some crowns were struck to a specimen finish, some were struck in sterling silver rather than the standard .500 silver and some were struck in gold (p81, Davies, British Silver Coins Since 1816, 1982).
Two die varieties of the crown occur - on most coins St George's sword points at a rim denticle but on some it points between rim denticles. Davies reports the the sword between rim denticles can occur on incuse edge proofs and possibly on circulation-style pieces too (p81, Davies, British Silver Coins Since 1816, 1982).
The Australian 2000 $1/10c mule is well known, having been discovered in the early 2000s. A number of other similar errors have since come to light - dated 2014, 2015 and 2020 - although their provenance is unknown, it is strongly suspected that they were illegally produced and smuggled out of the Royal Australian Mint.
A 2005 Dancing Man $1/10c mule was reported in the April 2025 Independent Coin News, having been discovered by collector Brendan Alves in February 2025 (Andrews, https://www.independentcoinnews.com/April_2025.pdf). Seemingly a Royal Australian Mint worker once again mistakenly used a 10c obverse die during the production of the 2005 Dancing Man $1 coins. $1 coins with double rims due to off-centre strikes are not uncommon, so most are disregarded as double strikes rather than mules, especially since the Royal Australian Mint is reported to have attempted to prevent the release of the 2000 dollar mules. This would explain why the 2005 mule went undiscovered for so long.
Currently only a single well-circulated example from circulation is known: no doubt there are others waiting to be found, but it remains to be seen if the error is limited to circulating coins or to just the Dancing Man $1 coins.
In 1964 the Heaton Mint in Birmingham struck Hong Kong's 10c pieces. All pieces were struck with a security edge rather than a milled edge, except for a single known piece struck with a milled edge and the letters HK repeated around the milling.
The nature of the piece is unclear but was no doubt an experimental piece, although it's not clear to what end - the security edge would no doubt be more difficult for forgers to replicate, but perhaps the costs associated with the security edge were higher than desired.
The single known example was offered for sale by Smalls Auctions' March 2025 sale as lot 217 but was unsold.