Gone are the days when obtaining a degree in a particular subject meant that the graduate would get a job in that field. The world is now pretty much your son's oyster as he has proved he is academic, (History being a good choice), and also self-disciplined enough to stick at his course. His next task is to practise selling himself to different employers and it may take several attempts before he actually decides on a future career path. Some of the most academic graduates I taught have surprisingly branched into fashion, media or IT, and I agree with mcem that "the most obvious routes aren't always the answer so keep an open mind."
Being in the capital also gives him the opportunity to get involved in so many things, including politics, so maybe he could look for research type jobs, or those in media or finance.
Self employment isn't all bad if he shows entrepreneurial flair and flexibility. The internet is a good place to start if he is tech savvy.
Good luck and give it time.