Until 1816, the guinea, worth 21 shillings, (1.05) was the main unit of currency in Britain.

The name came from the fact that the gold from which guineas were struck came from West Africa, which was generally known as Guinea at the time.
That name, in turn, came from a Moroccan word for 'black men' which was aguinaw.

Although the guinea has almost disappeared from common parlance, apart from the names of horseraces such as the Ten Thousand Guineas, it is still common to auction rams for prices in guineas.