He meets Mark Bennet, a vicar in Essex who was one of the brightest schoolboy mathematicians of his generation.
He won a gold medal and scored full marks in the International Maths Olympiad in 1981.
He went on to Cambridge, intent on staying there to become a professor.
Tiring of academic life, however, he entered the church.
Has he any regrets?
Chris Ledgard meets Mark Bennet, an Essex vicar who was a brilliant young mathematician.