The coin is minted from an alloy of 75% copper and 25% nickel. Between 1969 and 1997 the coin weighed 13.50 grams and had a diameter of 30.0 millimetres. In 1997 the coin was reduced in size to weigh 8.00 grams and have a diameter of 27.3 millimetres. Note that the coin is not circular but an equilaterally curved heptagon (seven-sided) to aid identification -- the sides are not straight but are curved so that the centre of curvature is the opposite apex of the coin, allowing the coin to roll freely in slot machines - a shape also used later for the Twenty Pence piece
This denomination has frequently been used for commemorative purposes, and consequently there are more design variations in this coin than in any other current British denomination.
The normal reverse of the coin, designed by Christopher Ironside, depicts the seated Britannia with a lion, with the numeral "50" beneath, and either NEW PENCE (1969-1981) or FIFTY PENCE (since 1982) above Britannia.
During the history of the coin, three different obverses have been used so far - between 1969 and 1984 the head of Queen Elizabeth II by Arnold Machin was used, between 1985 and 1997 the head by Raphael Maklouf was used, and since 1998 one by Ian Rank-Broadley has been used.
Up to 2003 there have been twelve varieties of 50p coin, six large and six small, as follows:
Large type 1: (1969-1972, 1974-1981). Obverse: Machin head, inscription ELIZABETH II D G REG F D date, starting to the right of the head. Reverse: Britannia and lion, 50 below NEW PENCE above.
Large type 2: (1973). Obverse: Machin head, inscription ELIZABETH II D G REG F D, starting to the right of the head, no date. Reverse: Nine clasped hands, 1973 50 PENCE in the centre -- commemorates the UK's accession to the European Economic Community. The design originally had the world 'EUROPE' in the middle, but this was vetoed by the Foreign and Commonwealth Office.
Large type 3: (1982-1984). Obverse: Machin head, inscription ELIZABETH II D G REG F D date, starting to the right of the head. Reverse: Britannia and lion, 50 below FIFTY PENCE above.
Large type 4: (1985-1993, 1995-1997). Obverse: Maklouf head, inscription ELIZABETH II D G REG F D date, starting to the bottom left of the head. Reverse: Britannia and lion, 50 below FIFTY PENCE above.
Large type 5: (1992-3).Obverse: Maklouf head, inscription ELIZABETH II D G REG F D, starting to the bottom left of the head. Reverse: Conference table with seats and stars, 50 PENCE below, 1992 1993 above. This coin was issued to commemorate the completion of the EC single market and the British presidency of the EC. Never commonly found in circulation.
Large type 6: (1994).Obverse: Maklouf head, inscription ELIZABETH II D G REG F D 1994, starting to the bottom left of the head. Reverse: An invasion force of ships and planes, 50 PENCE to the right. This coin was issued to commemorate the 50th anniversary of D-Day. Never commonly found in circulation.
Small type 1: (1997). Obverse: Maklouf head, inscription ELIZABETH II D G REG F D 1997, starting to the bottom left of the head. Reverse: Britannia and lion, 50 below FIFTY PENCE above. Issued only in 1997, but in very large numbers as it had to replace all the earlier types of 50p coin, which were withdrawn from circulation within 6 months.
Small type 2: (1998-date). Obverse: Rank-Broadley head, inscription ELIZABETH II D G REG F D date, starting to the bottom left of the head, IRB under the bust. Reverse: Britannia and lion, 50 below FIFTY PENCE above.
Small type 3: (1998). Obverse: Rank-Broadley head, inscription ELIZABETH II D G REG F D date, starting to the bottom left of the head, IRB under the bust. Reverse: Looks like a firework display of 12 stars with 1973 EU 1998 underneath and 50 PENCE below. Commemorates the 25th anniversary of Britain joining the EU. 5 million minted, but not often found in circulation.
Small type 4: (1998). Obverse: Rank-Broadley head, inscription ELIZABETH II D G REG F D date, starting to the bottom left of the head, IRB under the bust. Reverse: Caring hands holding sun's rays FIFTIETH ANNIVERSARY above and 50 PENCE below, NHS repeated 5 times around the border. Commemorates the 50th anniversary of the National Health Service. 5 million minted, but not often found in circulation.
Small type 5: (2000). Obverse: Rank-Broadley head, inscription ELIZABETH II D G REG F D 2000, starting to the bottom left of the head, IRB under the bust. Reverse: Open book above pillared building inscribed PUBLIC LIBRARIES 1850 2000 above and 50 PENCE to the right. Commemorates the 150th anniversary of the Public Libraries Act of 1850. 5 million minted, but not often found in circulation.
Small type 6: (2003). Obverse: Rank-Broadley head, inscription ELIZABETH II D G REG F D 2003, starting to the bottom left of the head, IRB under the bust. Reverse: Suffragette chained to railing holding a banner inscribed WSPU in her left hand, 50 PENCE to the left and a billboard inscribed GIVE WOMEN THE VOTE to the right, with 1903 below and 2003 to the right. Commemorates the centenary of the Womens' Social and Political Union (the Suffragettes).
See British coinage for other denominations.