Born in 1901, Haley grew up in Jersey and attended Victoria College. In 1918 he began to study journalism, and in 1921 he secured his first newspaper employment at The Times, eventually being stationed in Brussels. Early in his career on the Manchester Evening News, Haley was found to be too shy to work as a reporter. He was then transferred to subediting. He rose through the ranks becoming director of Manchester Guardian and Evening News after eight years.
He served as Director-General of the BBC from 1944 to 1952 and from 1952 to 1966 he was editor of The Times. While at the BBC he created the Third Programme, now known as BBC Radio 3. He was made Knight Commander of the Order of St Michael and St George in 1946.
He was editor in chief of Encyclopædia Britannica from January 1968 until resigning in April 1969 in an editorial dispute over how to adapt the work to new readers. It was reported that younger executives (including the company's president, Charles Swanson) wanted to introduce livelier materials, while Haley favoured the traditional approach and an expansion in size.
Sir William died in 1987 in a nursing home in Jersey.
