Your guide to decimalisation


11 February 2021
Decimalisation is the conversion of a system of currency to units divisible by 10. In the UK, Decimal Day took place in February 1971 and saw the old money of pounds, shillings and pence replaced with new pence and new coins, such as the 50p.

Decimalisation explained

From 15 February 1971 a new currency system was introduced to the UK, with the pound being made up of 100 new pence. Decimal Day saw the old system of pounds, shilling and pence, replaced with an entire new system and set of coins. 

As you would expect for such a dramatic change to how people managed their finances, the UK government issued a great deal of guidance on the subject, giving members of the public the information they needed to make sense of the new money.

This information was distributed by the Decimal Currency Board (DCB) and included television adverts and leaflets.

Indeed, the British public had years to come to terms with the idea, with the actual decision to go decimal made in 1966, following a reportedly brief and decisive conversation between Chancellor of the Exchequer Jim Callaghan and Prime Minister Harold Wilson, though a report had been issued suggesting the move in 1963.

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How the 'old money' worked 

Before Decimal Day (15 February 1971) there were 12 pennies to the shilling and 20 shillings to the pound.

Today this system seems confusing, especially to younger people who never used it. 

The system dates back to Roman times, when a pound of silver was divided into 240 pence, or 'denarius'. Romans used librum, solidus and denarius, or L, s, and d, the 's' and 'd' abbreviations survived until decimalisation, whilst the Roman 'L' gradually changed to the '£' sign still in use today.

The coin system in use in the UK was as follows: 

  • 2 farthings = 1 halfpenny
  • 2 halfpence = 1 penny (1d)
  • 3 pence = 1 thruppence or thru'penny bit (3d)
  • 6 pence = 1 sixpence (also known as a 'tanner') (6d)
  • 12 pence = 1 shilling (commonly referred to as a bob) (1s)
  • 2 shillings = 1 florin ( a 'two bob bit') (2s)
  • 2 shillings and 6 pence = 1 half crown (2s 6d)
  • 5 shillings = 1 Crown (5s)
  • £1 coin = 1 Sovereign
  • 1 guinea = £1, 1s, 0d, one pound and one shilling

Decimal Day in the UK

New 5p and 10p coins – the same size and value as one and two shilling coins – were introduced in 1968 and the 50p coin followed in 1969, although at that time it was referred to as the 10-shilling coin, as this was the value it replaced.

New 1/2p (half), 1p and 2p coins were introduced on Decimal Day, completing the new coin system.

The banks closed for four days before the change-over, and shop-keepers and members of the public were given special converters. Many shops published prices in both old and new money.

In February 2021 a new Decimal Day 50p was issued BY The Royal Mint to celebrate the fiftieth anniversary of the historic occasion.

Decimalisation around the world

Great Britain was rather slow in converting to a decimal currency system compared to other countries around the world.

Russia's ruble was updated in 1704 to equal 100 kopecks, and both France and the United States went decimal during the 1790s.

South Africa's successful decimalisation in 1961 put the idea back on the table for the UK government and a report was issued in 1963 recommending the move. Australia and New Zealand also went decimal during the decade.

The Decimal Currency Act was finally passed in the UK in May 1969.   

Further reading…

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