New style £20 bank note will be introduced from february 2020

The new design features the British painter JMW Turner, who's work is featured in the Tate Britain. For the first time, the new notes include two windows and a two-colour foil, making them very difficult to counterfeit.
The £5 and £10 notes which are already in circulation are made from polymer, as they last much longer than previous paper notes and stay in better condition, protected from wear and tear such as water damage.
The public can continue using the paper £20 notes, which will gradually be withdrawn when they’re banked. However, there will be a 6 months’ notice before the paper notes are no longer legal tender and cannot be received from hairdressers in salons.
A new £50 note will follow in 2021, featuring Alan Turing, who is best known for inventing the Enigma machine which was used for the British and allies to win the Second World War.