Short answers, pulled from the story.
The Secret Service Bureau opened its doors on the 1st of October 1909. It was established as a joint initiative between the Admiralty and the War Office to monitor the maritime strength of the Imperial German Navy.
Captain Sir Mansfield George Smith-Cumming became the first director of the Foreign Section in 1914. He signed all correspondence with his initial C written in green ink, a tradition that continues today among subsequent directors.
Soviet intelligence officer Konstantin Volkov offered names of all Soviet agents working inside British intelligence but Philby alerted the Soviets so they could arrest him. This incident marked the beginning of extensive compromise within SIS operations against the USSR.
Training for recruits takes place at Fort Monckton Portsmouth where candidates go through an intense six-month programme known as Intelligence Officer's New Entry Course. Recruits learn how to select and handle agents operate undercover identity use tradecraft skills such as dead drops surveillance and counter-surveillance techniques secret writing and code writing.
The existence of SIS was not officially acknowledged until 1994 when the Intelligence Services Act was introduced to Parliament. This act provides legal basis for its operations and subjects agency to public oversight by Investigatory Powers Tribunal and Intelligence and Security Committee of Parliament.