I made a fundamental mistake when pitching my Alan Turing script around town. They would all ask me how I found this story and I gave the wrong answer: “I randomly ran across it in a book, liked it, read a bunch more books, and decided to write it.” They would look a little uncomfortable and ask me what my connection to the material was, and I would blithely blabber, “Funny you should ask: absolutely none! He’s a gay British mathematician, and I’m not any of those things!” I didn’t realize that I was killing my sale.
Instead, when you’re pitching, you need to play up your authenticity, establish your connection to the material. Even if you don’t “own” any source material involved, you have to own it. Be necessary. Prove that you’re the one writer who is perfect for this material. Assure them that, if they had been the one to have this idea, and they could have hired any writer in the world to write it, you’re the writer they would have hired.
After all, as soon as they buy it from you, it is their idea, in every sense of the word, and you’re their employee. You don’t want them to suddenly wonder, “Why did I hire this guy?”
But be aware that there’s a tipping point at which your connection to the material stops being an asset and starts being a liability. It’s one thing to say, “I’m the perfect guy to write this, because I’m a gay British mathematician myself” (in fact, Turing’s most in-depth biographer was all three), but the fear is that you’ll then say, “And I’m gonna tell the real story, instead of all that phony Hollywood crap!” Suddenly, all of the enthusiasm will drain out of producers’ faces.
You have to own it without letting it own you. You have to have a deep reservoir of unique real-world knowledge, but then you have use it or discard it as necessary in the service of a great story.
Look at “The Americans”: creator Joe Weisberg sold that show based on his own experience as a CIA officer, and indeed the show offers many real-world aspects of spy work that you rarely see onscreen, such as the recruiting and handling of long-term assets, but it also exaggerates and re-writes the facts at will. The details are authentic, but the story is pure fiction.
AV Club interview, Weisberg makes it clear that the spy stuff was always restricted to being a metaphor for the family stuff, and never the other way around. He uses all of his spy knowledge, but he doesn’t let it take over the show. In the end, he’s not even writing about spies, he’s just using his authentic tradecraft knowledge as a source of unique details to enrich a universal story of family strife.