Gabriella Smart (in-universe)

Gabriella Smart was the sister of junior ringmaster David at Billy Smart's Circus, where she had a performing dog act.

Biography
The Third Doctor was driving to UNIT HQ in the Whomobile when he came across Gabriella crying at the roadside, because she had lost all of her dogs.

He helped her to find one of them, then drove her back to David — who was at the time in the circud's main ring where he was about to introduce the next act — to explain what had happened.

As Gabriella had only found one of the dogs, she and the Doctor went off in the Whomobile to find the rest of them. (TV: Billy Smart's Children's Circus)

Behind the scenes

 * Gabriella Smart portrayed herself in the television story Billy Smart's Children's Circus.