He got to inner circle and learned their plans, and the book was a narrative telling it in a different form that would not be dismissed immediately.

Huxley also was inner circle and was outing them in his work too.

Many people have said that the regime of the last 100 years has basically followed both scripts depending on the character of the people they are trying to subjugate. George Orwell's version is the one they use on those who refuse to submit to arbitrary authority. The rest are vulnerable to being drugged into robothood.