I used to have a corporate Amex, and it was a nightmare to use it in London. Even in places that said they accepted it, when I attempted to pay the card reader

I used to have a corporate Amex, and it was a nightmare to use it in London. Even in places that said they accepted it, when I attempted to pay the card reader rejected it. That was about 5 years ago, maybe times have changed - it would be great to see data rather than a mixture of anecdotes.