Exchange outdated British pounds?

You can still exchange old notes at the Bank of England and various post office branches.

https://www.bankofengland.co.uk/banknotes/exchanging-old-banknotes

If you are going to be in London, it is quite easy to go to the Bank of England and exchange.

https://www.bankofengland.co.uk/banknotes/exchanging-old-banknotes

We exchanged ours at one of the London post offices - very quick process.

It depends how old. I had "new pounds" that were refused. Goodness knows how I got the darn things.

If you have a lot to exchange you’ll probably need to go to the Bank of England (by the Bank tube stop) since post offices might not have sufficient funds on hand.

You might even get the "new" notes with King Charles on them. I have a couple.

The information for Post Office exchange is here, which includes a locator for the branches that offer the service:

https://www.postoffice.co.uk/banknote-exchange

The key info is that only the previous series can be exchanged, this is limited to £300, & ID is required.

If you end up at the Bank of England, the museum is good.
https://www.bankofengland.co.uk/museum

How much in pounds do you have? I had about £15-20 of old currency last year and put them in museum donation boxes.

Thank you so much, everyone! I received the "old" banknotes in 2019 so I think they're from the previous series. Unless there counting as the previous series the polymer notes with the Queen rather than Charles. I don't have much to exchange, certainly under £300. But I figure enough for a nice dinner out.
Thanks for the heads up about bringing my ID. And the limit.
It looks like there's a PO on Gloucester Road and on Earls Court Road near where we are staying but I could not find any indication as to whether or not either these branches could change the money. I did click on the filter services button but none of the choices included changing money. Anyway to find out? Or we could just go to the Bank of England. Looks like a fascinating area for historic London in any case.

I exchanged an out of circulation £10 note a few weeks ago (from a 2012 trip to London).

However, I didn’t exchange it in London, as I didn’t remember until I reached Scotland. Bank of Scotland had no qualms about exchanging it.

I did click on the filter services button but none of the choices included changing money.

It is under "Your Finances" in the filter with the check box being "Bank of England Banknote Exchange".

The nearest branches are Kensington or World's End, which aren't that close. Maybe pick somewhere close to where you are visiting on a particular day.

I have been to England three times. Each time I reduced the number of pounds that I got just because it was a pain in the posterior to find somewhere to exchange. Thankfully a post office was the more convenient, but still had to find one. This last time I exhanged $50 US for poundsos and was left with 10 pounds on our last day of a weeks visit. Fortunately, I walked right past a PO on the way to the train station and was able to exchange that. You can use a credit card for almost anything ..to include a taxi.

Now if you still wish to get pounds, please know that it's almost impossible to exchange any coins Especially if you bring them back to the US. So at least get rid of those when you can.