Ian Flemming's Rolex Explorer
It turns out that Ian Fleming wore a Rolex Explorer which you can see if you click on the photo of him below. I originally thought from the photos that he wore a Datejust or a Day-Date on an Oyster bracelet, but it has been confirmed that it was a Rolex Explorer.
I learned this from Mark020 from the Dutch Rolex Forum who shared the following images from the Imperial War Museum exhibition that is currently taking place in England to celebrate the 100th anniversary of Ian Fleming's birthday.
The photo below is of Ian Fleming's actual Rolex Explorer he wore.