A new design of pound coin is to be issued from 28 March this year. This will be twelve-sided like the old threepenny bit, although a smaller silver version will not be issued as well (there was once a small silver threepence coin which still appears in Maundy money and is still therefore legal tender for three new pence). The new coin will have a number of features to make it harder for forgers to copy it. It will be interesting to see what happens to these features when the coin becomes worn. Nickel-brass coins tend to wear quickly, and frankly they look horrible when they do become worn.
The existing round pound coin will be demonetised from 16 October 2017. You won’t be able to use it to go shopping after that date, or in slot machines. Many banks will probably still allow you to pay in the old pound after that date, on past experience, but it may be best to take no chances.
A new 50p coin featuring Sir Isaac Newton will also appear. Sir Isaac was Warden and then Master of the Royal Mint, and supervised the great recoinage of 1696. Prior to 1662, coins were hammered out by hand. After 1662 they were produced by machines, also called mills. In the 1690s a push was made to replace all the old hammered coins in circulation by the new milled coinage, which Sir Isaac was responsible for supervising. He is remembered with affection by accountants. This is the same person who is commemorated in Newton’s Laws in dynamics, Newton’s Rings in optics, and has a unit of force named after him.