John Schubert is one of America's sagely cyclists and cycling author. He possibly has forgotten more than most people who contribute to BFs know. I was browsing through one of his books, "Richards' Cycling for Fitness", published by Ballentine Books. Richard Ballentine is an English author who ranks with Schubert in knowledge. Now I've established the credentials, I'll quote the following:
"Drafting saves about one-third of the following rider's energy. What's less well known is that it also saves a tiny amount -- say, five percent -- of the lead rider's energy, the result of the way the air closes in behind".
I am happy enough with evidence for the prosecution.