I saw Bert Jansch at the Phoenix in 1968 (I think) on a visit, before I moved to London. Out of his head, unintellible vocally but marvellous playing, in between falling off the stool. The borrowed guitar story is certainly on sleeve notes of recordings of the time (Live in Glasgow/Young Man's Blues).
RtS (after I moved to London in late 1969 it was jazz clubs I haunted)