Philip John Lee - Black Scrag
https://youtu.be/2RpEWzaQlicThis is from a 1973 omnibus four sided album named "Guitar Workshop", some of it is on YT. Also on YT from this album is Davey Murrell's piece "Kenneth's Riverbank Song. Not on the Internet is David Bedford's eighteen minute experimental opus
Eighteen Bricks Left on April 21 the middle section of which is improvised on the understanding that the same must consist entirely of feedback and be as loud as possible, probably just as well 'cos it is atonal bollox.