Originally Posted by
Calchas
I have not tried this for RTW fares, but BA will happily quote in an arbitrary currency converted at the IATA exchange rate, independent of the selling country. I used to buy quite a lot of ex-Norway tickets priced at BGO and priced in GBP.

Good to know. I shall keep that in mind for my next xONEx
(currently undecided between starting with BA's CPT-LHR or IB's JNB-MAD)