Desmond Llewelyn was not the first choice for the role of Q. Peter Burton preceded Llewelyn as Q but for only one film, Dr. No (1962). In that movie, he was known as Major Boothroyd and Armourer. Llewelyn was only referred to as Major Boothroyd once in the James Bond movies, and that was by Roger Moore in the The Spy Who Loved Me (1977).
Desmond Llewelyn was the longest recurring actor in the EON James Bond franchise, appearing in 17 films, but his total on screen time only totals just over half an hour.
This short documentary is dedicated "In Memory of Desmond Llewelyn 1914 - 1999".
In real life outside of the James Bond movies, actor Desmond Llewelyn deplored gadgets and technology. Ironically, in these films, he often had to speak long passages of technical jargon.
The Q (Major Boothroyd) character appears in every James Bond movie (EON and non-EON productions) except three: Casino Royale (1954); Live and Let Die (1973) and Casino Royale (2006).