I've just tried to make a same-day change on a 'Plus' ticket (after midnight on the day of travel) which would have shifted my departure form one London airport to another. System offered a series of possibilities but anything other than same actual airport then triggered a (large) change fee.
Rang exec club to ask what the actual policy was, a very helpful agent said she didn't know but would find out - she came back with the info that at some point in Mar 2016, London airports (and maybe other 'groups' like NYC etc) became 'separate' in the BA systems, and therefore not eligible for same-day no-fee changes.
When I said I'd done this before (eg after the new fares came in) she suggested that was a glitch that BA then ironed out.
So a big possible plus of the new fare structure is now not possible.
