What do a bob, crown and guinea have in common?

After the Norman Conquest in 1066, the British pound was divided into 20 shillings or 240 pennies. Until decimalization in 1971, money was divided into pounds (£) shillings (s) and pennies [or pence] (d).

The symbols s (for shilling) and d (for pence) derive from the Latin solidus and denarius which were the names of coins used in the Roman and Byzantine empires. The £ sign developed from the latin word libra, which refers to weighing scales.

The shilling was subdivided into 12 pennies. The penny was, in turn, subdivided into two halfpennies or four farthings (quarter pennies). It was based on the troy system of weighing precious metals where the penny was literally one pennyweight (1,89 grams) of silver. A pound sterling thus weighed 240 pennyweights, or a pound (453 grams) of sterling silver.

There were also commonly used terms to describe particular denominations, for example:

Two farthings were one halfpenny (or hay-pence).

Two halfpence was one penny

3 pence was called thruppence 

6 pence was sometimes called a tanner.

5 shillings was a Crown whereas 2 shillings and 6 pence was half a crown

A shilling was also commonly known as a bob.

Although not commonly used, two shillings was also known as a florin or a two bob bit.

A £1 coin was called a Sovereign and was originally made of gold. A £1 banknote was, and is still, called a quid.

One guinea was one pound and one shilling or 21 shillings. A guinea was considered a more gentlemanly amount than £1. One paid tradesmen, such as a carpenter, in pounds but gentlemen, such as an artist, in guineas. During the early explorations, the Guinea coast was fabled for its gold and the name became attached to other things like a guinea fowl and Papua New Guinea.

Monday 15 February 1971 was known as Decimal Day in the United Kingdom and was the day on which the pound was decimalised (see the above video). Today, like most currencies, there are 100 pence in a pound.

POSTUM

South Africa decimalised in 1961 and changed to Rand and cents at the same time. Until this time, the country used the british pound and the same demoninations as above To help people adjust to the new currency, a song was released that got played heavily on the radio: it was called Decimal Dan and the Rand cent man.

This video from Australia (who changed to decimal in 1966) shows how difficult it was to work with punds shillings and pence!