The Farthing was a small circulating coin of the British pre-decimal Pound Sterling, equal to a quarter of a penny. Prices were never written in farthings though - something worth a farthing would be quoted as 1/4d ("d" being the abbreviation for "penny", from the Roman "denarius"). There were 20 shillings to a pound, 12 pence to a shilling and 4 farthings to a penny, so 960 of these coins made up £1.
The denomination continues the tradition of earlier farthing coins of Great Britain, which also featured the figure of Britannia. The bronze coins of this type replaced the larger copper farthings which were issued until 1860; copper was considered to be impractical as it wore too rapidly due to extensive circulation. The new, more durable, alloy was composed of 95 parts of copper, four of tin and one of zinc. The coins were also smaller and thinner, therefore more convenient to carry. The dies were engraved by Leonard Charles Wyon, then Engraver to the Royal Mint.
The reverse features a new, third, design of Britannia. The obverse carries Leonard Wyon's "Bun Head" portrait of Queen Victoria. Both sides were updated to the farthings carrying the fourth Britannia design and a new effigy of the Queen in 1895.
Farthings were demonetised before the rest of the pre-decimal currency. They ceased to be legal tender after 31 December 1960. In other words, farthings issued in 1877 remained in circulation for 84 years.
The 1877 farthings were struck in Proof grade only (probably at a later date); none were issued into regular circulation. | 
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