Usually they came first.

The silver penny, for example, was the functional everyday currency of the Anglo-Saxon English kingdoms from roughly the 8th century onwards, developing from the earlier sceatta coinage which spread through the network of wic trading sites proliferated along both sides of the English Channel and the North Sea. Although the pound existed as a conceptual unit of value - there were 240 pennies to the pound - it didn't exist as an actual unit of currency. More common used values were the shilling - 12 pence in Wessex and 4 in Mercia - and the Mancus. The Mancus did periodically exist as a gold coin equivalent in value to 30 pence, but mostly only as a ceremonial issue not designed for regular commercial use.

For reference, economic regulations in the early 10th Century established the trade value of a cow at around 20 pence, and the basic unit of measurement of arable land, the hide, was very, very roughly expected to produce an annual income of around one pound. By the 10th Century, English pennies were actively designed to be split into halves and quarters to facilitate lower-value payments.

Functional higher-value coinage arrives later. The numismatic reforms of Edward III in the 14th Century introduced the popular groat coinage with a value of four pence, and the first commercially successful gold coinage, the noble, which had a value of 80 pence, or 6 shillings and 8, a third of a pound. The pound didn't actually become a useable unit of currency in Britain until the introduction of the One Pound note by the Bank of England in 1797 after a gold shortage impacted the availability of the Sovereign, a gold coin introduced in 1489 by Henry VII with a value of one pound one shilling.