He used green ink. It was "special" green ink. And that was the least of his eccentricities.
He wore a gold-rimmed monocle and carried a sword-stick.

He told numerous tall tales of heroism to explain his missing leg, which he lost in car accident. He was known to startle visitors by sticking his wooden leg with a letter opener or penknife. He got around the office by placing his wooden leg on a scooter and used his good leg to push the scooter through the hallways.

On more than one occasion he traveled to Germany posing as a German, although he didn't speak a single word of the language.

He collected all the latest gadgets of every description, from guns to nautical pieces. He collected boats and cars. He was particularly fond of his Bentley, which he drove through the city at high speeds, sometimes with his 12-year-old niece at the wheel.

When he hired people, as often or not he hired them because they admired a book in his collection or could talk knowledgably about arcane subjects. Somerset Maugham was just one of his many famous employees.

His name was Captain Sir George Mansfield Smith-Cumming, and he was the first head of the modern British Secret Service. Known as "C" (not M, as in the Ian Fleming books), his distinctive green ink was the unmistakable mark of his authority. Both his title and green ink have been used by every office holder since.