A scientific notebook compiled by World War Two codebreaker Alan Turing has sold for $1m in New York.

The handwritten notes, dating from 1942 when he worked at Bletchley Park, were entrusted to mathematician Robin Gandy after Turing's death.

Cassandra Hatton, director of history of science and technology at Bonhams, said it was the only time that a handwritten document by Turing had ever sold in auction.