Decimal Day weights and measures.) Around the time of Decimalisation Day, "Decimal Adders" and other converters were available to help people convert between the old and new coins. The following is a table showing conversions between the decimal and pre-decimal systems. All pre-decimal coins (except for certain non-circulating coins such as crowns, sovereigns, and double florins which were explicitly excluded from demonetisation) are now no longer legal tender. Public outcry at the proposed demise of the old sixpence (6d), worth exactly p and originally slated for early withdrawal, postponed its withdrawal until June 1980. Shillings and florins, together with their same-sized 5p
One pound (British coin) a new 12-sided design, was introduced in 2017, the earliest dated as 2016. The coin has a 12-edged shape, similar to the pre-decimal brass threepence coin; it has roughly the same size as the previous £1 coin, and is bi-metallic like most £2 coins. The new design is intended to make counterfeiting more difficult, and also has an undisclosed hidden security feature called "iSIS" (Integrated Secure Identification Systems), thought to be a code embedded in the top layer of metal on the obverse of the coin, visible only under a specific wavelength of ultraviolet light. Current two-pound coins, being bi-metallic