The new Bank of England banknote featuring Matthew Boulton and James Watt has entered into circulation.
The pair feature on the new note partly because they were instrumental in manufacturing coins that were difficult to counterfeit.
There are about 210 million £50 notes in circulation worth £10.5 billion.
The new version of the £50 banknote has a thread woven into the paper, rather than printed on it. There are also images on the thread of a £ symbol and the number 50 which move up and down when the banknote is tilted from side to side.