Decimalisation formally occurred in February 1971. However, in 1968 decimal coins were introduced for those denominations that exactly matched old £/s/d coins or bills: the 5p coin replaced the shilling, the 10p replaced the florin, and the 50p coin replaced the 10s note. Sixpence coins also circulated for a while because they were equivalent to 2.5p.
When decimalisation occurred, old half-pennies and pennies were replaced with "new pence", and all other old denominations such as half-crowns were no longer valid. The 20p coin was introduced in 1982 to help with change-making because too many 10p coins were being used. A £1 coin was introduced in 1983 to reduce the demand for paper currency because £1 notes wore out too quickly. The new half-penny was eliminated in 1984 because its purchasing power had fallen to the point where it was no longer useful.
The first decimal coins were the same size as their pre-decimal equivalents, which proved to be unwieldy in the long run. For example the 5p coin was the same size as the old shilling which was once a fairly high-value coin, but by the 1990s its purchasing power had declined to the point where it was a minor denomination; having more than a few of them in your pocket got to be pretty inconvenient. To simplify things the Royal Mint introduced new 5p, 10p, and 50p coins that were much smaller than their predecessors.
The scheduled date for introduction of the British decimal coins was the 15th of February, 1971, but some coins were issued a few years earlier.
The 10 and 5 New Pence coins were both first issued in 1968 and circulated together with the Florin and Shilling respectively that they replaced.
The 50 New Pence coin was first issued in 1969 and circulated together with the Ten Shilling bank note which it replaced.
The Two, One and Half New Pence coins were all released as scheduled in 1971.
From an historical perspective, the Florin (Two Shillings), being one-tenth of a Pound, was an early, half-hearted attempt at decimalisation in 1848.
British decimal currency was scheduled for the 15th of February, 1971, but the 5 and 10 New Pence coins were issued much earlier in 1968 and circulated along with the similar sized 1 and 2 Shilling coins they were to replace.
In British Decimal currency, the One Pound coin was first issued for general circulation in 1983. The British Two Pound coin was first issued in 1985 as a collectible gold coin. It was first issued as a nickel-brass Commemorative in 1986, and as general circulation coin in 1997.
The British decimal One Pound (nickel brass) coin was first issued in 1983. A gold One Pound coin was issued from about 1489 until 1604.
The first British 10 Pence coin was issued in 1968 as part of the conversion to decimal currency.
Such a coin does not exist. The British have never issued a "cent" coin. The 5 New Pence coin was first issued in 1968.
The first British 50 New Pence coin was issued in 1969.
There has been a British Five Pound coin on and off since 1817. The British decimal Five Pound gold bullion coin was first issued in 1980 and the Five Pound "Crown" coin was first issued in 1990. The current British Five Pound "Crown" coin is intended to be a non-circulating legal tender commemorative coin. The Royal Mint has no current plans to produce a general circulation Five Pound coin in the foreseeable future.
The British 20 Pence coin was first released in 1982.
Such a coin does not exist. The British 50 Pence coin was first issued in 1969.
Such a coin does not exist. The British One Pound coin was first issued in 1983.
There were no British 1975 25 Pence coins issued.
Such a coin does not exist. The British - 1 New Penny was first issued in 1971 2 New Pence was first issued in 1971 5 New Pence was first issued in 1968 10 New Pence was first issued in 1968 50 New Pence was first issued in 1969
The first British 20 Pence coin was issued in 1982.