Glide, regardless of what you think of BA's attitude towards you, you do give the impression that whilst it isn't alright for you to be treated like that it would be alright if they were offering an interview to a clerk.
Is that really what you meant???
If you had turned up for the interview I believe that you would have gained merit for the fact that you were prepared to travel such a distance to get there, might even have given you an initial advantage over the locals. I fancy the sandwich was just a red herring and irrelevant..The fact that you didn't go is ok because it was your decision but you have reduced your opportunity to get a job by 33%, I hope you don't regret it.
I hope you are successful in your jobseeking but please remember that in any organisation most people at all levels, pilots or clerks, are trying their best and therefore should be respected for that...