Alexander Christian
Alexander "Lex" Christian was a human astronaut who travelled to Mars as a member of the United Kingdom's 1970s Mars missions. He was framed for killing his fellow astronauts on Mars; they were in fact killed by Native Martians. He was at some point under the command of Alistair Gordon Lethbridge-Stewart.
In 1997 while being transported by helicopter, it crashed. He escaped, coming across Smithwood Manor. After stealing money and supplies, he located Lethbridge-Stewart and explained to him what really had happened on Mars and the likelihood of a Martian invasion of the United Kingdom. (PROSE: The Dying Days)
Other information
Alexander knew Jo Grant when she was studying her A levels. (PROSE: The Dying Days)