Because of the large number of pennies in circulation there was no need to produce any more in the 1950s, however a large number of specimen sets were issued in 1953 for Elizabeth II's Coronation. At least one 1954 penny was struck, apparently for private internal purposes at the Royal Mint, but it was not until 1961 that there was a need for more pennies to be minted, and production continued each year until 1967, and afterwards (as pennies continued to be minted with the date 1967 until 1970). The 97% copper, 0.5% tin, 2.5% zinc alloy was used again for the 1960s pennies. Finally, there was an issue of proof quality coins dated 1970 produced to bid farewell to the denomination.