h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

A couple of observations ..... the guinea was also the unit of payment for tailors.

I believe it was more than a "notional" unit. I think the guinea was minted (as a silver coin, larger than a crown, with St George & the Dragon on the reverse) until early in the 20th century.

(Great article, btw!)

We might add that the Guinea was also used as prizes or gifts given in recognition of some action. C.S. Forester makes reference to Hornblower receiving a sword of "100 Guineas Value" in "Captain Hornblower." This title, by the way, was for the trilogy of "Beat To Quarters," "Ship of the Line," and "Flying Colors," or "Happy Return" as it was known in England.

In 1851, the yacht "America" won the "100 Guinea Cup" in its race around the Isle of Wight. This cup has come to be known as "America's Cup." The cup, which was in existance since the early 1840's, presumably cost 105 Pounds Sterling to create. A further bit of trivia: the cup has no bottom.

These were simply two examples of the Guinea as a prize or recognition gift, adding to an already intriguing article.

Guineas for prizes came via horse racing, I think. Certainly they were real coins once, but I've never seen one. Only expensive tailors? There used to be a company called "The fifty shilling tailors" where I remember an uncle having something made. He was thought to be "silly with his money" by the rest of the family, who could only afford "off the peg"
What's the use of a cup with no bottom? I thought such trophies were supposed to be drunk out of by the victors?

The guinea was a gold coin minted from gold mined in Guinea, a former British holding in NW Africa. It was originally valued at 20 shillings, the same as a sovereign, but as the prices of gold and silver fluctuated, it was revalued to 21 shillings. Auction houses and horse traders used to value their wares in guineas long after the coin disappeared from circulation.