Keats wrote the immortal words "Silent upon a peak in Darien" while riding the Number 4 omnibus to Kettering. Having composed the phrase, but with no paper handy, he repeated it to himself over and over until he was ejected from the 'bus at Burton Latimer, which forced him to walk the rest of the way. Ironically, the line is utterly forgotten now, by everyone.
Most of Bertolt Brecht's plays were actually written by Elizabeth of Glamis, the future Queen Mother. The two had an affair lasting seven years, until Edward VIII abdicated and Elizabeth was forced to abandon Germany, her growing Marxism and her anti-borgeouis stance for unwanted luxury and nationalism.