Here's a recent article from the FT [1] (paywalled):

> Across the country, there are now barely 4,000 bank and building society branches, down 80 per cent in 40 years.

So, a big decline, but still 20x as many high street banks than what a 99% decline claims.

[1] https://www.ft.com/content/10ce1086-a9ae-4851-92e4-3b6efc8a0...