Cook joined the BBC as a film critic in 1934 and, shortly afterwards took on the additional role of London correspondent for the American network NBC.
He became an American citizen during the Second World War while travelled in the USA for the BBC. When the war ended, he started work on a radio narrative called 'American Letter'. The programme, later re-named Letter From America ran for 58 years.
Cook was greatly respected on both sides of the Atlantic, being awarded an honorary knighthood by the Queen and addressing the US Congress on its 200th anniversary.
American Letter 1947 – BBC Home Service
Letter from America – 2002