Marc Sullivan features in this Danish documentary from '67.
http://youtu.be/sjEsRWGxVLM

He played in a band called 'Proof Spirit' with John Bidwell and others. Sadly he died a while back. I'd also be interested in any further news anyone has about him, or any recordings. John Bidwell last saw him in the early '90s and has said this about him "Marc just didn't realise how brilliant he was. Remember how he used to stay up all night at our gaff, and in the morning he'd have half a dozen songs written. Beautiful guitar arrangements and all"