Assured that he was not being forced into anything, Sigma began to relax again. "Very well," Sigma begins, sitting up straight. "My name is Sigma Klim, or Zero, as some Tributes call me." That probably didn't matter, and he mentions it with a dismissive wave of the hand. He had already told the Doctor that 'Sigma' was fine. "I am 69 years old, and I was born on July 18th, 2006." He wonders if that would mean anything to her, or if it would be a date from the distant past.