]Some interesting points here. To go back to the point about o/w differencex, some fare rules specifically state this :
IF A RETURN TICKET SHALL BE USED FOR ONE WAY TRAVEL THE DIFFERENCE BETWEEN THE RETURN FARE AND THE APPLICABLE HIGHER Y/J/F-CLASS ONE WAY FARE HAS TO BE COLLECTED
How and if that is enforceable is another story, but theroetically, that's how it is.
ExXB :
Internationally there is limited need for a ow product. Almost everyone returns. Emigrants, ships crews and students who are the exception qualify for their own fares usually.
It's a little more complex than that. When multi-sector fares are constructed, combinability rules have to be considered. This is why, for example, if you travelled AAA-BBB-AAA using the same carrier both ways, you would have more low fares available than if you travelled out and back on different carriers (excetion being if those carriers were in an alliance codeshare).
Taking this a step further, if you want a journey LON- MAD - BUE - SCL - MIA - LON and you 'mixed' carriers, you might find that the fare quote would give you the sum of one way fares on each sector, which would be rather like building a car from spare parts! If you chose carriers where the fares were combinable, you would perhaps get a half round trip fare LON -SCL and antoehr half round trip for SCL - LON, bearing in mind that a 1/2 RT is not the same as a one way. Then of course the question of pro-rates as mentioned comes into play, and where the fare is broken and how it is constructed materially impacts the value to each carrier of its coupons.
None of this answers the original question:
On that basis, why does BA seem to be exerting its pricing power only at Heathrow and not City as well ?
I don't know! Does anybody?