Carter was an MI6 agent.
Carter was sent with Morris to walk along a canal, looking for a "1950s police box". They spent some time looking and eventually came across it. Carter reported in to control, but as she did so, some Cybermen appeared and attacked, killing them both. They then used her mind to talk to North on the telephone. However, the Eighth Doctor noted that the voice was incapable of telling a joke and told North they were dead. (COMIC: The Flood)