Re: The d in £sd
It's actually a pretty simple system which was very long lasting.
4 (copper) farthings/fourthlings to a (copper) penny.
3 pennies to a (silver) threepence
6 pennies to a (silver) sixpence
12 pennies to a (silver) shilling.
20 shillings to a (gold) pound coin with a value of one pound of silver coins.
These coins kept their value (and therefore inflation damn near flat) from the 8th century through to the 19th century and the advent of paper currency where "I promise to pay" [in base metal] appeared, with the promise secured on the collective wisdom and honour of politicians.
Shortly thereafter we went with debased coinage (literally coinage no longer made from base metals) and currency and inflation has exploded.
In 1800 you could buy a bread loaf for around two and a quarter pence (this was high; as a result of bad harvests and wheat shortages.) In 1930 the same sized load cost two pence. In 2022 it's around £1.30 so a twopence had a purchasing power well over a modern pound.
Biting the hand that feeds IT
