Guineas
As noted, a guinea was worth 21 shillings, or one pound (20 shillings) plus 1 shilling. There was a guinea coin until the early 1800's, when it was discontinued. But for some reason, sellers of luxury products continued to price their goods in guineas, so that right up to the time of the introduction of decimal currency, a Rolls Royce, or a fur coat, or a diamond necklace, would usually be priced in guineas. Likewise, many professional fees were also set in guineas, so that your solicitor might send you a bill for 100 guineas for the costs of your lawsuit against the Harley Street specialist who charged you 5000 guineas to remove your tonsils. Of course, when you paid your solicitor, your check was for £105/-/-.