Here's a little segment of an article from the London Telegraph about the book:
His [Dahl's] social skills attracted the attention of famous Canadian spymaster William Stephenson, who was running a clandestine British effort to draw America into the war.
Antoinette Marsh Haskell, the daughter of Marsh, explained that with Dahl's status came a string of women.
She said: "Girls just fell at Roald's feet.
"I think he slept with everybody on the east and west coasts that [was worth] more than $50,000 a year."
Despite Dahl's reputation as "one of the biggest cocksmen in America", as described by previous biography, he was said to have passed on several useful pieces of intelligence, including his belief that President Franklin D Roosevelt was having an affair with Crown Princess Martha of Norway, who had been granted asylum by the US.