Around 63 million £50 banknotes bearing the portrait of the first governor of the Bank of England Sir John Houblon are to be withdrawn from circulation in 15 weeks' time.
From April 30, only the £50 note which celebrates the 18th century business partnership of entrepreneur Matthew Boulton and engineer James Watt, who helped forge the Industrial Revolution, will hold legal tender status, the Bank of England said.
> Around 224 million £50 notes worth £11.2 billion are in circulation, of which the Bank estimates 63 million with a total value of £3.2 billion are Houblon notes.
From May onwards, retailers are unlikely to accept the Houblon notes as payment, but most banks and building societies will still allow customers to deposit them into their accounts. However, agreeing to exchange the notes after April 30 will be at the discretion of individual institutions.
Barclays, NatWest, Royal Bank of Scotland (RBS), Ulster Bank and the Post Office have agreed to exchange the older-style £50 notes for both customers and non-customers up to the value of £200 until October 30.
If people do not pay in or exchange the Houblon £50 notes by the withdrawal deadline, this does not mean that the notes then become worthless.
All notes that have been issued by the Bank whose legal tender status has been withdrawn are covered by its "promise to pay".
This phrase dates back to times when notes could be swapped for gold. It means that people can, at any time, obtain the face value of a note that has been withdrawn by exchanging it at the Bank of England in London. There is no fee for the service and banknotes of this type can be exchanged by post or in person.
Legally the Bank of England is only required to give one month's notice of an intention to withdraw legal tender status. It gave a similar three-month notice period to its latest announcement when a £20 note featuring composer Edward Elgar was withdrawn in 2010.
Sir John Houblon was appointed as the Bank's first governor in 1694 and the £50 banknote celebrating him was first issued in 1994, to coincide with the Bank's 300th anniversary.
The design on the back of the note includes an image of Sir John's house in Threadneedle Street on the site of the Bank's present building.
The withdrawal of the Houblon note is part of the Bank's regular review of notes to make them more secure and combat fraud. The Boulton and Watt note, which was brought into circulation in November 2011, was the first introduced by the Bank to feature a green "motion thread'', which has five windows featuring the pound symbol and the number 50, which move up and down when the note is tilted from side to side.
In December, the Bank announced that it plans to issue plastic banknotes for the first time from 2016, when a new £5 note featuring Sir Winston Churchill appears.
A £10 note featuring Jane Austen to follow around a year later will also be made from polymer rather than the cotton paper currently used.
The announcement at the end of last year followed a three-year research programme that concluded plastic notes stay cleaner for longer, are more difficult to counterfeit and are at least 2.5 times longer-lasting.
Old-series notes previously issued by the Bank can be exchanged by posting them, at the sender's risk, to Dept NEX, Bank of England, Threadneedle Street, London EC2R 8AH.