"Although we liked the idea of a story that would allow Cat to return to the show, the writers basically said that if we lose Cat then we also lose Sam. I wasn’t part of that main group of friends; if Cat suddenly decided that she didn’t want Sam or Frankie and that she was going to go and get a job in London, Sam wouldn’t just start hanging out with that crowd. Her story would come to an end. So it was quite flattering that they said, “we have to kill Cat in order to keep you.” The only way the group could unite with Sam was through that grief over Cat’s death."
~ something I did not know about “Lip Service” via Autostraddle — Heather Peace Gets Honest: The Autostraddle Interview