Proof? Well, if proof is the man himself clearly saying he wrote it, Ewan McColl that is, then there certainly IS proof. I've never heard the story saying this other guy wrote it by the way! I'm sure McColl must have told the story a few times, but I well remember he and Peggy Seeger appeared on Radio 2's Folk on Two in the early 80's, and as best I remember, McColl had either been travelling to America or just returned. He phoned Pegy from the airport. She was about to do a show, she told him she was in need of one more song, a ballad, for her set. He told her he had a 'song in progress' And give him 5 minutes he'd finish it. So he completed the song on the back of a Park Drive Cigarette packed, rang her back and dictated it to her, hence the song was born. I'm sure BBC Radio can confirm that. I've also read the very same story in at least tw books. McColl also said the royalties (from the hit version) Enabled him to complete several Folk archive projects. P.S he said he wrote the song About Peggy