1982 AD., Great Britain, Elizabeth II, 20 Pence, KM 931.

United Kingdom, Elizabeth II, London mint, engravers: Arnold Machin (obverse) and William Gardner (rev.), 1982 AD.,
20 Pence (21.4 mm / 4,94 g), curved seven-sided (equilaterally curved heptagon), copper-nickel (84% Cu 16% Ni alloy), mintage 740.815.000 , medal alignment ↑↑,
Obv.: ELIZABETH II / D· G· R E G· F· D· , diademed bust of Elizabeth facing right (first portrait). The border is raised and the border inscriptions are incuse.
Rev.: TWENTY - PENCE / 19 - 82 / W - G / 20 , crowned Tudor Rose, with the value numeral below rose, flanked by engraver´s initials and the year. The border is raised and the border inscriptions are incuse.
KM 931 . issued from 1982 to 1984.

At mint state the twenty pence coin weighs 5,00 grams and has a diameter of 21.40 mm. The Twenty Pence coin was introduced in June 1982 to fill a very evident need for something to fill the gap between 10p and 50p. It was very quickly accepted by the population as a whole. It is arguably the most common of the 'silver' coins found in change.
While the 5p, 10p and 50p coins are made from a 75% Cu 25% Ni alloy, the 20p is made from an 84% Cu 16% Ni alloy. The reason for the use of this alloy is to alter the electrical conductivity to allow discrimination by vending machines. It uses the maximum amount of copper while retaining a 'silver' appearance. Despite this the alloy is slightly yellower than the usual 75% Cu alloy.