Originally Posted by
AirbusA350
Irrespective of the BA country website OP would have purchased it from, if his booking was indeed an ex-UK/Channel Islands/IOM/Gibraltar itinerary, it would have charged him in GBP regardless of whether that was booked through BA’s UK/US/Irish/Indian/Spanish/etc websites.
Not necessarily, BA can charge you in whatever currency you want. I've had BA charge me for an Ex-Italy flight in Canadian Dollars for example.