Originally Posted by
AnnaZ
1) You can only upgrade by one class with BA air miles (so Economy to Business would not be possible even if I had enough air miles to do so)?
...
We have been told this by someone at BA (on the phone) but I'm not sure if I can trust this information as points on the BA website that suggest that this is not the case (though the info on the website is very ambivalent, hence my confusion).
You may be being confused by the information on the website that
also deals with flights where the only two cabins are business and economy (eg BA short-haul flights from London to European destinations). In this case, you can upgrade from economy to business because it's a one-cabin upgrade.
But if the flight has business, World Traveller Plus and economy, then you can only upgrade with miles from economy to WT+, or from WT+ to business.
And in both cases, there are the other restrictions too that have already been mentioned, particularly that you can only upgrade from economy if you're booked into Y, B or H booking classes.