Originally Posted by
Rousseau
So, for pre-booked economy flights that I want to UuA retrospectively, I will only ever be able to do this if they are semi/full flex?
Only if they are booked in Y, B or H booking classes - that's what you need to look for. It doesn't actually matter what the underlying fare rules are.
In any event, "semi-flex" means little on BA these days. Almost all fares can be described as semi-flex. The only routine exceptions are the cheapest fares in Club (both CE and CW).