LGW CE flights have had this ability for some time, although it's not well known (hat tip to c-w-s who advised me) and you will likely have to get the airport and/or call centre staff to dig very deep into the record if you need them to make the change (for example, if you've already checked in).

As to whether the system is confused between a LGW & LHR departure, or this is a sign of good things to come - well, I'll leave that to your best judgment! I think I'd be tempted to retain the screenshot in any case though ...