Part 12 in shipping different railway companies together, I guess this, like Part 10 isn't exactly a ship.
May I introduce you to the London Airport Express Group. They aren't a relationship or anything, just a LinkedIn group of airport workers in and around London. They work on a fast, frequent and efficient working.
The group consists of:
Heathrow Express, she is the prestigious and classy one.
Gatwick Express, he does a fast intercity service serving a much larger region out of anyone in the group.
Stansted Express, she is the dedicated in the group but still works well, though doesn't work quite as efficiently.
Other people want to join the group:
East Midlands, who doesn't operate a proper direct service.
Greater Anglia, who doesn't even try to work efficiently.
Elizabeth Line, which does work is kind of accepted as a friend of the group as she was a friend of Heathrow Express' now dead sister (Heathrow Connect).