Originally Posted by
Gshumway
For economy only the 3 most expensive booking types will allow upgrade via Avios one class up. If the booking type is Y, that would allow upgrading into WT+ if inventory is available.
Thanks Gshum. I am aware of the booking class restrictions for upgrading BA tickets; that was not what I asked. The question is whether BA looks at the fare basis or the booking class to determine eligibility.