I think situation in 2021 is very different in London: AMEX is accepted nearly everywhere in central London (Even on markets etc), there are ofc some shops that don't take it but generally AMEX is widely accepted.
Re: Mastercard
It seems that Mastercard is more widespread among "hot" banking startups, ie I can create virtual debit Mastercards on Revolut and Monzo
Re: Mastercard
It seems that Mastercard is more widespread among "hot" banking startups, ie I can create virtual debit Mastercards on Revolut and Monzo