For what it is worth, on my trip to the UK last month, I was given a bill in US dollars, but only once. It happened to be the first purchase I made in Edinburgh (forgot my jacket at home!). I gave my credit card and the bill listed the price in pounds, the conversion fee, the price in dollars, but no conversion rate. The fine print at the bottom said something like "I understand I have been given a choice of currencies and I accept this bill as stated".

I protested that I had not been given a choice and I wanted to pay in pounds. He weakly said that he had to charge me in dollars, but then quickly acquiesced and gave me the bill in pounds.

It was the only time that happened in the 18 days we were there.

Bryan in Oakland, CA