Back in the day it was inadvertently referred to in the Pentagon's annual publication "Soviet Military Power" - according to Flight International the document was hastily gathered back in at a press event when one of the journos noticed it...
So in answer to your question, it definitely did exist on paper.
Edited to add: I'm sure some people hereabouts will be familiar with the story about some unknown & allegedly secret US mil aircraft having a mishap at Boscombe in the nineties or early noughties, resulting in much activity on the site with screens erected etc etc.