I wrote this article at the same time as the other one.

The main unit of the British monetary system is the pound. Before decimalization of the system in 1971, these were the values of British coins.

1 pound = 20 shillings
1 shilling = 12 pennies (or pence)
1 penny = 2 halfpennies
1 halfpenny = 2 farthings

1 half-groat = 2 pence
1 threpence = 3 pence
1 groat = 4 pence
1 sixpence = 6 pence
1 florin = 2 shillings
1 half a crown = 2 shillings and sixpence
1 crown = 5 shillings
1 guinea = 1 pound and one shilling, or 21 shillings (a guinea was considered a more prestigious form of money)

Pounds are sometimes called sovereigns (specifically a gold coin pound - first minted in 1817) or a quid. A sixpence could be called a tanner, a shilling a bob, and pennies were sometimes called coppers.

Bank Notes came in various values.

Slang terms for large amounts of money, often used by gamblers, were:
pony = £25
monkey = £500
plum = £100,000
blunt = money

A vowel is a regency slang term for an IOU.

Regency slang terms for being in debt:
"In Dun Territory"
"Pockets to Let"
"Purse Pinched"
"Punting on the River Tick"
"Rolled-up"
"Run Quite Off One's Legs"