Unless things have changed in the last 4 years I've been abroad, £50 notes are basically unused/deprecated anyway. In my entire 25 years I was living there I had never received one from an ATM, and even when I withdrew large quantities of cash from the bank branch itself it was always denominated in 20s and 10s. I've seen people trying to pay with them (usually foreigners, having exchanged the notes in their home country) and getting denied because cashiers are unfamiliar with them and couldn't tell a fake from a real note to save themselves. If you put a gun to my head I couldn't tell you what a Bank Of England 50 looks like without googling it - pink maybe? Only reason I know the Bank of Scotland one is because it won some award a couple years back (if you're into pretty banknotes take a peek here http://www.theibns.org/joomla/index.php?option=com_content&v...)

That said, removing them would be kinda silly IMO. It may solve the awkward "tourist buying a £3 beer with a £50 note" scenario, but you have that pretty much everywhere. I kick myself when I forget to hit the "Select bankotes" option at ATMs here because a 2000 CZK note is pretty tough to spend. That's maybe more because Czech bars/shops are awful at stocking their cash registers with enough notes for the day and the cashiers just simply do not have the change available.