A new £50 banknote with the image of Matthew Boulton and James Watt is now in circulation with several security features to try to lower the risks of forgery.
Instead of the metallic thread printed onto the paper, this has been woven into the note and there is a hologram image on the thread of a £ symbol and the number 50, which move up and down when the banknote is tilted.
The note also has a see-through panel, a ultra-violet strip and micro lettering below the Queen's image.
Boulton and Watt were chosen for this banknote because of their role in creating coins that were difficult to counterfeit.
This is the first time in history that two people will appear on the reverse of a banknote. The pair are famous for bringing the steam engine into the textile manufacturing process as well as dealing with money problems in the late 18th Century.
The banknote will replace the £50 note with Sir John Houblon's image on it, which was first introduced in 1994. But this will still remain legal tender until the Bank of England announces a withdrawal date. After then, you will still be able to deposit the notes in most banks, building societies and Post Offices in customer accounts.
There are currently around 210 million £50 notes in circulation and this amounts to £10.5 billion.