In the movie War Horse, a horse is purchased at auction for the price of 30 guineas. At the time the movie is set, circa World War I, 30 guineas were equal to £31 and 10 shillings.
Before 1971, British money was counted on a different scale than it is today. It was based on:
1 pound = 20 shillings
1 shilling = 12 pennies
A guinea (first issued on February 6th, 1663) was sometimes used as a unit of account. A guinea was a gold coin, originally made of gold from the Guinea coast of Africa, worth 21 shillings (or one pound and 1 shilling) in old British money. A guinea was considered a more gentlemanly amount than £1. A gentleman paid his tailor in shillings, but his barrister in guineas.
One shilling is now equal to five (new) pence making a guinea worth one pound and five pence in today’s currency (£1.05).
Let’s take a look at the history behind the changing coinage in our pockets, featured at Telegraph.co.uk.