The Air Canada fare sale that Kevin mentioned last night does not seem to extend to passengers from the UK. Leastways the price they are currently quoting me for Worldcon in August is almost twice what I have paid for the staff meeting trip in April.
However, I did notice that I mis-booked my hotel room. I really should be leaving on the 11th, not the 10th. So I went to the web site to change it, only to discover that they have no record of my booking. I think I shall be phoning Canada later today.