Deep Throat was Mark Felt who was the associate director of the FBI in the 70s who was also the key man in bringing down President Nixon's US Government in 1974, over the Watergate scandal. He died today, aged 95.

Here's some background info: Richard Nixon was in power, and was a bit of a bastard, and was using his power to cover up the fact that he was a bit of a bastard. Then, two journalists - Bob Woodward and Carl Bernstein - with the help of Deep Throat (who had all the goss on Nixon and his administration) found out what was going on, told everyone, and Nixon resigned.

To cut a long story short - Deep Throat was a bit of a dude. And no one had a bloody clue who he was until 2005, when he publicly revealed himself and solved one of the biggest mysteries of American politics and journalism. The actions of Woodward, Bernstein and Throat are documented in the excellent All The President's Men, a clip of which you can see above. Blinding.