Ireland 1961 Mule variety Half Crown Rare Very High Grade Coin. The 1961'mule' halfcrown was struck in error (or, possibly deliberately) from a reverse die from the 1928-37 type.In 1938 the halfcrown reverse - the side with the horse on it - had been redesigned to improve the striking characteristics of the coin. A single example of the 1938 trial of the new die exists. During the preparation of the 1961 re-strike of the 1928 proofs the original dies were tested and found not to be in suitable for use in producing the new proof coins.
In this process the halfcrown die from the 1928 series was (deliberately or otherwise) introduced into the production run for circulating 1961 halfcrowns.