Originally Posted by
rwm818
I was just in London - and was able to exchange at a bank.
I heard that the 20£ is next to be changed out?
Yes, many commercial banks will still do the exchange for non-customers, but there are no banks in LHR.
There appears to be a Barclays at Hatton Cross which is accessible by free buses from all terminals.
The £20 note will be replaced by a polymer version in 2020.
The BOE says there are "no plans" for a polymer £50, and the Treasury recently launched a consultation regarding scrapping £50 notes (although they shelved plans in the same consultation to scrap 1p and 2p coins due to some disingenuous MPs and media outlets making an outcry).
However, the £50 note was only recently changed in 2011-14 (the dual-circulation period lasted for 2½ years), and based on recent patterns it is not due for a redesign until a few years either side of 2030.