This used to be fairly common but you see it less these days, or fewer people discuss it.

It happens when a company, and multinationals like Amazon are the obvious ones, charges your card in a foreign country but in Sterling. Most UK Amazon transactions are actually made in Luxembourg for tax reasons.

Creation doesn't actually look for transactions in foreign currencies, it looks for transactions initiated outside the UK which is why you get double.

It’s not known when or even if Marriott will relauch it’s UK Mastercard/Visa offering. But don’t forget there is still the SPG AMEX which pays a very generous 3 points per £ on day-to-day spending and 6 per £ spent at Bonvoy properties. Although AMEX is not as widely accepted here in the UK as it is in USA, it is accepted across petrol stations, supermarkets and major retailers. Now it does carry a £75 ($100) annual fee but I have it and make about £8,000 each year general spending on it. Added to my £7,000 annual Bonvoy spending makes a total of 66,000 points. If I did this on my legacy Marriott Creation card I’d receive 24,000 including the annual 2k bonus. The extra 42,000 points are easily redeemable at £250 making the annual AMEX fee well worthwhile!

Finally AMEX does have a scheme where if referred you get extra sign-on points, as does the referrer, so do ask me to refer you if you’re going to give it a whirl.