Originally Posted by
satprof
...For JanoS-, I'm sure that the UK origin for the LONEx will mean that the UK price applies, although I believe it would be charged in CHF (converted at BSR - Business Selling Rate) if ticketed in Switzerland, e.g. by AA Zürich.
No, unless Switzerland joins the EU by the ticketing date -- the rules are very clear, buy in Switzerland means the ex-Swiss price applies even for UK origin. You must buy in the country of origin to get that price, or in one of the exempted countries (Canada and now the EU with this relatively new EU rule). Purchase in any other country means the price ex-that country applies (even if you never fly to/from that country on the ticket).
The price is charged per the fare rules (always GBP for ex-UK). Conversion is per country of sale and further possible converted by the payment instrument. Example: buy ex-UK in Canada using US credit card. Price is in GBP converted to CAD at the airline rate. Charge is then converted by the credit card company to USD (plus their usual 1-3% exchange fee).