My girlfriend and I are booked LCY-GLA-LCY on an upcoming weekend on June, departing LCY at 2015 on the Friday. (We were originally booked on the BA8740 at 2110, but that's since been cancelled.)

She's just found out she needs to be in Birmingham for a meeting during the day. This makes it a bit of a mad dash back down to London and a putting a lot of faith in public transport on a Friday afternoon.

The ideal situation would be for me to get the original flight, and for her to get the train from Birmingham to Glasgow, but of course no-showing for the outbound would mean she would forfeit the return (and mine too?)

Given that it's not a flexible ticket, I assume there's no way to cancel one outbound and keep the return. I'm struggling to find any benefit in moving to the 2100 departure from LHR or 2115 from LGW given that any time gained by a later flight would be eaten up by security/compliance.

Any sage advice from FlyerTalkers, other than to leave Birmingham in good time, and keep everything crossed that there aren't any delays?