In the films there have been varying interpretations of Bond's military rank but in the books at least, it was not a cover or an honorarium but a reflection of Bond's service during World War II, in the Royal Navy (though it is also thought by Bond scholars that his background must reflect service with SOE, the Special Operations Executive). Daniel Craig's Bond appears to have served in either the SAS or SBS (Vesper Lynd, in Casino Royale, refers to "ex-SAS types with easy smiles and expensive watches") before joining MI6, but in You Only Live Twice, The Spy Who Loved Me, and Tomorrow Never Dies (this year marks the 50th, 40th, and 20th anniversaries of the three films respectively) Bond is portrayed in his Royal Navy uniform.