Originally Posted by
lhrsfo
Being based in London with Amex as my primary card and MC as my backup, I do about 35 transactions per month on Amex and 3 on MC.
The OP should be aware that, without a Chip and PIN, no card will work in machines (parking, tube tickets etc. ) and contactless is needed to replicate an Oyster Card.
I was able to use my pin-less (chip and sig) Amex to buy tube tickets, train tickets, and get a Boris Bike at the automated machines. It just didn't ask for a pin. Which is slightly concerning, but it worked.
I had a handful of restaurants in London that wouldn't take Amex, but at least 90% of my charges were on it. I'd assume outside big cities it might be accepted less, but I stick with cities.