Graham was born in Manchester, England. His first novel, Ross Poldark, was published in 1945, and was followed by a series of eleven further titles, the last of which, Bella Poldark, came out in 2002. The series was set in Cornwall, where Graham spent most of his life.
Aside from the Poldark series, Graham's most successful work was Marnie, a thriller which was filmed by Alfred Hitchcock.