this raises another similar question i have: historically i have learned and just accepted there is no such thing as being able to move to an earlier flight on BA much like you can with AA (for example) domestically and recently on longhaul. it is free for OWE, space permitting.
anyhow the other week i landed at LAX at 9am and have the 9pm on BA back to LHR and before venturing out i went to check in and just asked if i could move to the 330 to LHR despite knowing i was on an ex-DUB restricted ticket. he typed a few things in and without question moved me to the earlier flight.
was this just a generous agent? luck?