Britannia (NEW PENCE) 50p (1969 to 1981)

The large 50p was demonetised in 1998, so this coin is now worth only what collectors will pay. Circulated coins from 1969, 1970 and 1976 to 1981 are plentiful and sell for modest sums, which means condition does most of the work: crisp detail on Britannia's figure and shield and little wear on the rim lift a coin. The proof-only dates of 1971, 1972, 1974 and 1975 are valued as set coins, and the 2019 small-size reissue from the anniversary sets is priced on its own.

With 594,917,500 struck for circulation, the Britannia (NEW PENCE) 50p is the 80th rarest of the 81 ranked 50p designs and has the 177th lowest mintage of all 194 circulating UK designs. That puts it in the Common band, for mintages 10,000,000 or more.

The next rarer 50p is the Royal Shield 50p, with 353,590,405 struck, and the next more common is the Britannia (small) 50p, with 805,926,100 struck.

Its lowest circulation mintage was in 1970, with 19,461,500 struck.

Size gives it away at once: this is the large 50p, 30 mm across and far heavier than any 50p in change today. Turn it over and read the words above Britannia. NEW PENCE marks this version; large coins dated from 1982 read FIFTY PENCE instead. The date and Arnold Machin's portrait are on the heads side. No Britannia 50p is dated 1973, the year the only 50p was the EEC hands design, and coins dated 1971, 1972, 1974 or 1975 came from proof sets.

Known varieties of the Britannia (NEW PENCE) 50p, all listed among the UK error coins and varieties:

• 2019 small-size reissue: The NEW PENCE reverse was struck again dated 2019 on the small 27.3 mm coin with the fifth portrait, for the brilliant uncirculated 50 Years of the 50p sets. Not issued for circulation.

The 50p went into circulation in October 1969, well ahead of Decimal Day in 1971, as the coin that would replace the ten shilling note, and until decimalisation it was spent as ten shillings. Its shape came from the Decimal Currency Board, where the engineer Hugh Conway chose a seven-sided curve of constant width: measured in any direction it gives the same breadth, so it rolls and passes through vending and sorting machines like a round coin. It was the first seven-sided coin in the world, and not everyone welcomed it; a group calling themselves the Anti-Heptagonists called it ugly. Christopher Ironside's reverse shows Britannia seated beside a lion, a shield resting against her right side, a trident in her right hand and an olive branch in her left. The words NEW PENCE run above her and the numeral 50 sits beneath the figure. The heads side carries Arnold Machin's portrait of Queen Elizabeth II. The same reverse was struck again in 2019 on the smaller modern 50p for the 50 Years of the 50p sets.