Sherman Pegg
Should be Sherman Pegg. The story establishes his full name.
Talk about it here.
Sherman Pegg (born 1971) was a fifteen-year-old American boy who developed an idea for time travel in a science competition in 1986.
Biography
Sherman entered a science fair with his theory on time travel. He made a model representation of this theory using a basketball. He called it The Way Forwards. Sherman met the Second Doctor and Victoria Waterfield at the fair. The Doctor made changes to Sherman's formula. The Doctor did not expect Sherman to understand his corrections, but he did. Sherman used the machine and caused major changes to the timeline. The Doctor agreed that he would help Sherman win the fair once time was back on track. (AUDIO: The Way Forwards)