According to Savile biographer, Alison Bellamy, the former BBC host positioned himself as a somewhat "informal chief advisor" to Charles.
Following the Lockerbie bombing, the Pan Am flight that blew up over the Scottish town of Lockerbie, killing 270 people, Savile imparted advice on reacting to major public incidents. He told Charles an incident room with numerous phone lines should be set up and the Queen should be "advised in advance of any proposed action of family members".
It appears Charles whole-heartedly took on Savile's ideas, replying in another letter: "I attach a copy of my memo on disasters, which incorporates your points and which I showed to my father, and he showed it to Her Majesty."
In yet another letter, the prince asked Savile if he would meet with his sister-in-law, the Duchess of York, telling the presenter Fergie would do well to hear "some of your straightforward common sense".
The docuseries also looks at how Savile, who was described by The Guardian as a "prodigious philanthropist" and received a knighthood in 1990, positioned himself as a public relations advisor making efforts to influence the British ruling class, including the royal family and former British prime minister Margaret Thatcher.
After Savile's 2011 death hundreds of survivors came forward to reveal stories of abuse.