Yep.
Someone nondescript.
Neither terribly ugly, nor dashingly handsome.
An everyman, easily overlooked.
A social chameleon who could become charismatic through dress and charming behavior, or invisible through affected dullness.
The perfect spy.
Ian Fleming learned the craft and the requirements during the second world war. He wasn’t imagining a Hollywood heartthrob. He was creating a semi-plausible character.