The £1 note was finally withdrawn in 1988 by the Bank of England, but Scottish £1 notes are still printed, I believe.
There has also been talk from time to time of withdrawing the £5 note with a £5 coin intended for circulation, instead of the more commemorative £5 crown coin we have at the moment. But as it happens, we are switching to polymer notes in 2016 and this includes the fiver so I doubt we'll be withdrawing it anytime soon.
Polymer notes are said to be cheaper to produce, harder to counterfeit and they are more durable, so perhaps the US Mint could switch to polymer in the future, if they haven't already.