Ok, got a call back from a supervisor today, and had an interesting chat. Basically, ticketing won't ticket it as it has to be billed in GBP if I want to pay in the UK, not GIP, and even though it's 1:1, they won't do it - which he apologised for. He was very helpful, and he's going to give GIB a call now, and get the tickets debited from there, and call me back.

Update:

What a performance. The guy from BA in the UK called back saying GIB wouldn't ticket it as it wasn't a GIB based credit card. He was very apologetic about it all.

So I called GIB back myself, and explained the situation. The lady was a little surprised, but checked with the supervisor and said that they did take UK based cards. Oh. Excellent. Here's the number. Five minutes later she called back to say it's ticketed. Got all the ticket numbers, appears in checkmytrip.com correctly. All sorted, tickets to be picked up at the airport on the day of the flight. :)

Moral of the story:
BA in Gibraltar ^
BA in the UK :td:

It's not BA's fault. Ticketing rules state that ticket must be paid for and issued in the country of origin.

Small update, the BA Amex bill arrived today.

Triple miles posted.

No Forex fees for being billed in GIP. The amount on the bill in GBP was the same as the GIP amount. :)

Tickets are to be picked up at the airport on the day of departure.

Seems to so far have worked out quite well.

Topping this because of what I saw in this thread on the BA board: http://www.flyertalk.com/forum/showthread.php?t=386777

I'm not enough of an expert in these mythic matters to know whether I should race to get ticketed on an ex-WAW or -IST OWE before Jan 15 or not sweat it. Can someone explain (in "Fare Construction for Dummies®" style) what this might mean for OW RTWs?

It would seem that daniellam's comment at the bottom of the linked thread would minimize the interest in racing anywhere. I think he's one of the guru-class pundits. Of course OWE fares are trending upward on their own seemingly faster than inflation so it doesn't hurt to plan ahead as far as your finances allow.