Display showing a pile of sterlings balanced against a pound weight
The basic unit of currency in medieval England was the silver penny or sterling, weighing 1⁄240 of a tower pound. 240 of these coins made a "pound of sterlings". This term (shortened to "pound sterling" in later usage) continued to be used for a sum of 240 pence even after the sterling had ceased to circulate. The modern pound sterling is equivalent to 100 new pence.
1668 July 3rd, James Dalrymple, “Thomas Rue contra Andrew Houſtoun” in The Deciſions of the Lords of Council & Seſſion I (Edinburgh, 1683), page 547
Andrew Houſtoun and Adam Muſhet, being Tackſmen of the Excize, did Imploy Thomas Rue to be their Collector, and gave him a Sallary of 30. pound Sterling for a year.