Samantha Briggs
From Tardis Wiki, the free Doctor Who reference
Samantha Briggs was the sister of Brian Briggs. When he disappeared while taking a Chameleon Tours trip to Rome, she went to Gatwick Airport to investigate, and teamed up with the Doctor to find the other missing persons.
Behind the Scenes
Samantha was originally intended to become the Doctor's full-time companion at the end of The Faceless Ones but Pauline Collins turned down the offer to become a series regular. Consequently the supporting character Victoria Waterfield from the following story The Evil of the Daleks was chosen to be the next companion.
Pauline Collins returned to Doctor Who in the 2006 adventure Tooth and Claw to play Queen Victoria.
