Homeward Bound, Mary/Matthew, spoilers for the third series

Mary takes the premium shuttle back to her home moon from Londinium. She could have asked Matthew or even Edith to have flown her there and back in one of the family’s fleet of spacecraft, but then there would have been questions that she didn’t want to answer. The treatment is complete now, the nanites are fully integrated and she is assured that her body will be able to carry the next Crawley to term.