Let's look at various banks' total assets, as listed on this random website i found [1], in millions of pounds: Monzo 139.82 Starling

Let's look at various banks' total assets, as listed on this random website i found [1], in millions of pounds: Monzo 139.82 Starling 206.64 Marks & Spencer 5569.90 Ulster 11641.00 Metro 21647.00 Co-operative 23102.80 Coutts 34280.00 Clydesdale 43583.00 HSBC (retail) 238939.00 Barclays (retail) 251305.00 On that measure, at least, Metro Bank is a hundred times bigger than either Monzo or Starling. Assets are not the whole story, of course; i'd be interested to see numbers for customers, revenues, and some sort of measurement of payment flow. But i think the lesson here is that if you live in the London tech bubble, it's easy to think that Monzo are huge. Many of my friends bank with Monzo, and i see plenty of Monzo cards being tapped on the readers at the tube station. But we are not representative of the country at large. [1] https://thebanks.eu/banks-by-country/United-Kingdom https://thebanks.eu/banks-by-country/United-Kingdom