Originally Posted by
britbronco22
However I'm talking about the situation where you can choose to be charged in £ or FX (for example choosing between buying something at LHR or at your destination), if the price is the same you choose the £, unless you are actually getting extra points to cover the FX charge.
Nevertheless, the extra cost is only somewhere in the region of 3%. If you're earning 12.5 miles per £1 on what you've spent, that's still a cracking good deal whether you've paid 103% or 100% of the GBP purchase price. And even if you've paid wrongly 103%, you're still getting extra miles on that 3%, at a price of 0.8p per mile.