Six coins 1877 1880 1889 1891 1892 as with the lower denominations a switch was made to bronze in 1860 with the introduction of what has always been known as the bun penny the diameter was reduced from 34 mm to 3081 mm and the thickness significantly reduced the new coin was half the weight of the old at 94g and was officially coined at 48 pence to the pound these dimensions remained the same until 1970 the composition of the new coin was based on that adopted by france in 1852