As Merlen was not eligible for a full-time post at the Royal Mint, he was hired on a temporary basis, with a salary of four guineas (84 shillings)-a-week, equivalent to £400 as of 2025.

[1] Merlen's effigy is also notable for being the first to show a male monarch bareheaded, i.e. neither crowned or laureate (in the style of Roman emperors) since the reign of Edward VI.

Pistrucci had designed an 1820 gold double sovereign three years earlier although this was never issued for general circulation and, as such, is deemed to be a pattern coin and of the highest rarity.

Merlen also designed several reverses, the most widely used being a crowned shield surrounded by a wreath, variants of which were used in issues of William IV and later Queen Victoria.

Merlen continued to work alongside engraver William Wyon during the early part of Queen Victoria's long reign.