Thomas Brewster

Thomas Brewster was a orphan and street urchin from Victorian London.

Thomas met the Doctor and Nyssa while he was being haunted by what he thought was his mother. After the Doctor helped him, he stowed away in the TARDIS and accidentally set it on a solo flight (BFA: The Haunting of Thomas Brewster)

As the TARDIS began to self-destruct, Thomas was helped by an elderly Adric, who helped him return to London, a few months after his departure. The Doctor then invited him to join him on his travels. (BFA: The Boy that Time Forgot)