The guinea was a coin, minted in Great Britain between 1663 and 1814, that contained approximately one-quarter of an ounce of gold. The name came from the Guinea region in West Africa, from where much of the gold used to make the coins was sourced. It was the first English machine-struck gold coin, originally representing a value of 20 shillings in sterling specie, equal to one pound, but rises in the price of gold relative to silver caused the value of the guinea to increase, at times to as high as thirty shillings. From 1717 to 1816, its value was officially fixed at twenty-one shillings.
Five-guinea coin, James II, Great Britain, 1688
George III, "Spade" issue, 1795
King Charles II
King James II, with elephant and castle under the bust, 1686
Sterling is the currency of the United Kingdom and nine of its associated territories. The pound is the main unit of sterling, and the word pound is also used to refer to the British currency generally, often qualified in international contexts as the British pound or the pound sterling.
The Hatter's hat shows an example of the old pre-decimal notation: the hat costs 10/6 (ten shillings and sixpence, a half guinea).
A pound = 20 shillings = 240 silver pennies (formerly)
King Offa penny (eighth century)
Penny of Henry III, 13th century