Major Simon Ordell was a member of the Royal Marines. During his tour of duty, he was part of a friendly fire incident, in which he was blameless, but the Perseus Corporation arranged the evidence so that he appeared at fault.
He was assigned as a UN military adviser to Perseus Dynamics on their Peacekeeper project. He had been there for two years when the company's computer system was hacked. He accompanied the Eighth Doctor during his investigations into the attack.