Here is what I found in Oldfield's book (p.44 on the french edition) :
Around the same time (note from JF :the previous page from the book is about Mark and Sue hercombe, so the "around the same time" isn't very accurate), Mark was able to make a record. Dave: "a guy who did the markets, I believe, paid Mark to go to London to record a demo. They went into a real studio and record it in half an hour, an hour. It was never released, I think no one has ever done anything with it, either, it just happened. He never claimed it to be of superior quality, it was a demo. A really good song called "summer's coming my way", good for its time. Given what it was and what he had in hands, it was really a brave effort. He was still really in the folk clubs in the time ".
sorry for the bad translation, I used Google and corrected what I can, in order to be the closer to the book