Post medieval period spans the history of the Tudors, Stuarts, Georgians, and finally the Victorians.
The Great Debasement (1544–1551) was a currency debasement policy introduced in 1544 England, under the order of Henry VIII, which saw the amount of precious metal in gold and silver coins reduced and in some cases replaced entirely with cheaper base metals such as copper. The Great Debasement policy continued under Edward VI, with silver content dropping to only 25% in the mid 16th century. Debasement was revoked in 1551 and silver fineness restored to 92.5%.
Up to this point in history coins were made by hand hammering metal between two dies, hence they are known as hammered coins. During the 16th century, some milled coins were produced under Elizabeth I using a horse powered screw press at the Tower of London. These were of far higher quality than the hammered coins but met with distrust from the public and opposition from mint workers, leading to the experiment being abandoned.
There were further sporadic trials of milled coinage under Charles I and Oliver Cromwell, then finally in 1662 under Charles II hammered coin production ceased, with all new coins being machine struck. All the old and worn hammered coins were finally withdrawn from circulation in the 1690s when Isaac Newton was in charge of the Royal Mint.