[dcminter]

Most Brits pay with debit cards or credit cards. This leaves an audit trail.

https://www.ft.com/content/afe8ed5a-cd10-11e5-986a-62c79fcbc...

I think you're conflating twoo things as well. Retailers don't like high denomination notes because they're more likely to be forgeries (getting change from a low value purchase with a high denomination note is a simple way to launder forged notes)

Governments don't like them because of tax evasion (though they'll call it "anti money laundering because not all upstanding citizens are entirely averse to a spot of cash-in-hand money laundering).

I presume there's just enough demand from business (where using high denomination notes for high value B2B transactions has very low transaction costs) that they still print them, but I would be surprised if they're still around in a decade.