Most of us will be familiar with the inscription “Decus et tutamen” that has appeared on the milled edge of most British £1 coins ever since the “round pound” replaced the Bank of England pound note in 1983.

The phrase “Decus et tutamen” was first suggested 350 years ago this month, on 10 January 1662. The proposal came from the scholar and writer John Evelyn, who made the suggestion directly to Charles II when coins were being designed for the new king’s reign. Evelyn’s idea was put into practice on valuable coins such as the gold five guinea piece.

The inscription seems to have disappeared after Charles II’s death, but it was resurrected during later reigns for use on precious commemorative coins.

“Decus et tutamen” means “an ornament and a safeguard”. This refers to the inscription itself, the purpose of which was to deter coin-clipping — or, as Evelyn described it, “this injurious Practice of Clippers”.

Coin-clipping was the act of shaving off a small portion of a precious metal coin for profit. The clippings could be saved up and melted into bullion or used to forge new coins.

The law considered clipping to be as serious as counterfeiting. Both practices were widespread in the late 17th century, when they almost bankrupted the country.

Coin-clipping could even be punishable by death. In 1690 Thomas and Anne Rogers were convicted of high treason for clipping 40 pieces of silver. He was hung, drawn and quartered and she was burned alive.

Evelyn wrote that the phrase “Decus et tutamen” came from “a Viniet [vignette] in Cardinal de Richlieu’s Greek testament”. But the original appearance of the phrase is attributed to Virgil’s Aeneid, which includes the words “viro decus et tutamen in armis”, describing a piece of armour, a breast-plate interwoven with gold, that was awarded as a prize to one of Aeneas’s senior officers.