Marc Brunel
Marc Brunel was a scientist from Earth.
In the 1820s, he was expected in a scientific meeting in Killingworth sponsored by Lord Ravensworth and hosting George Stephenson, among the others. The meeting was supposedly cancelled after the plots of the the Rani and the Tremas Master, thwarted by the Sixth Doctor. (TV: The Mark of the Rani)
The Sixth Doctor read his name in a collection of business cards of geniuses to consult for a problem of time slip. (TV: The Two Doctors)
The Sixth Doctor met him in 1828, and helped him to investigate a strange creature. He found a strange city when he went to inspect the outside of the tunnel. He wanted to bring an expeditionary force into the city under the Thames. (AUDIO: Iron Bright)