Hello - I'm not usually on BA but this time schedule to Fly paris - sfo via LHR. However, I'm in london now and i can't get to paris by train. So does BA allow me to skip the first part? Or do i have to fly to Paris in the morning to do the leg? I'm on a discount CW fare flying tuesday 12th - i know the weather may be better then but i can't get to Paris tomorrow so I'm cancelling my things there. Thanks in advance for any information on how BA allows (or not) skipping a leg