Anvil Jackson

 (real name David Jackson) was a former human trafficker who fled from his old life and assumed a new identity as a self-proclaimed war hero. He thought an anvil was a hammer. He was held prisoner and experimented upon by the Sontarans before the Seventh Doctor helped him escape. When the Bloom probed his mind, he confessed to his crimes and his false identity. (AUDIO: Terror of the Sontarans)