I think part of it is coloured by Mike being in Canada, as am I; and for many years BA has used Canada as a place to make easy money. Over the years I have noticed many times than a Canada ->UK fare is much higher than a corresponding UK->Canada round trip. If anything a trip starting in the UK should cost more because of APD, but that hasn't been the case in my experience over the years. Instead, it seems AC and BA until fairly recently have had a rather comfortable duopoly they were both happy to exploit.

Certainly on the 787 I'd say the fares ex Canada in Y don't reflect what the passengers receive, but people pay it because most people want to fly non stop.