More thanks for posting this selection of Jon's recordings on Youtube and reminding us what a considerable talent was lost to us those years ago.
I only heard Jon perform once, at Harrogate Folk Club when it was at the Irish Club on East Parade, probably spring or early summer of 1971 not long before he was killed. On that occasion representatives of the local bench of magistrates turned up to see what these young people were getting up to with their folk music. They went away greatly impressed. If Ray Black, folk club organiser at that time follows this forum he may be able to confirm these details.