Jason Steed is an agent with SYUI.
If you have not heard that acronym before, do not feel alone. Steed certain had never had any inkling of it before he was literally waylaid on a road at night by its director, George Young, with a request that Steed join the organization. Steed would soon learn that it stood for "Scotland Yard Undercover Intelligence".
That will not be the only British intelligence organization that Steed will have contact with; the first he dealt with was likely, though never specified, MI6 as they were out to recover a casette tape which, if in the wrong hands, could lead to nuclear explosions killed hundreds of thousands.
All that is pretty heady stuff for any operative. Imagine what it would be like for an 11-year-old boy! That is what Steed is when we first watch him get involved in cloak and dagger activity.
We actually start up with Steed in his earlier years. The only child of Raymond Steed, an officer in the Royal Navy, his mother had died in child birth and he was raised by nannies in the British Colony of Hong Kong for the first decade of his life as his father was constantly away on duty cruises. We are there in 1969 when at age 5 he was passing by a window of a dojo and saw people inside practicing martial arts. He was immediately fascinated.
Over the next couple of years his studies in hand-to-hand combat would progress phenominally with black belts earned in karate, judo, kung fu, tae kwon do, and jui jitsu. In what spare time he had, he found a way to sneak into a military facility with flight simulators and he taught himself the basics of how to fly.
Steed's involvement with SYUI will come from his already making a name for himself in the first recorded adventure where he helps prevent a nuclear war. True, he did not start out that day planning on doing that. He was in the wrong place at a very wrong time. Staying alive was a particularly high priority; he just took it upon himself to help others which resulted in his saving the day.
The amount of notoriety, which he worked hard to keep to a minimum, would bring him to the attention of SYUI and some interesting missions on their behalf. Said assignments taking place when there was no schoolwork or he was not spending time with his girl friend, Catherine. Oh, did I mention she was the daughter of the Queen of England and therefore a princess?