New Zealand 1965 Halfpenny Mule
Through the 1960s, the Royal Mint was busy striking coins not only for the United Kingdom, but also for a number of other members of the Commonwealth: the decimalisation and independence occurring in many of these countries created a busy time for the Royal Mint. Although New Zealand had not yet converted to decimal currency and was already independent, their bronze and silver coins were part of the Royal Mint's workload in 1965: it is in this environment that a 1965 New Zealand halfpenny was accidentally struck with a British halfpenny obverse.
Only one 1965 New Zealand halfpenny mule is known and it shows signs of a small amount of circulation - it is possible that more may exist but more than likely the mix-up was discovered and almost all examples were caught. The provenance of the one example is unknown but it was last sold as lot 1602 in Downies auction 313 in February 2013. It had previously been listed in British coin catalogues (p30, Perkins, Collectors' Coins GB, 2011).