In the Novel Cryptonomicon Lawrence Pritchard Waterhouse an American Wartime cryptanalyst is in London with as he describes Massive British Coinage that clanks in his pocket like pewter dinner plates.
Decimal coinage was adopted as the official currency of the United Kingdom on February 15, 1971, One Pound Sterling made up of one hundred pence. Pre-decimal coinage was more complicated in its denominations.
£1 = 20 Shillings = 240 Pence.
1 Shilling = 12 Pence = 2 Sixpences = 4 Threepences
1 Penny = 2 Halfpennies = 4 Farthings.
In addition there were other coins.
1 Crown = 2 Halfcrowns = 5 shillings.
1 Florin = 2 shillings.
Listed below are the diameters in mm and weight in grams of the various denominations of coin during World War II.