The guide has the FA as Allen Bancroft 1976
The write up in Mountain 43 is fairly clear
At Millstone Edge, Ron Fawcett and Pete Livesey climbed Coventry Street free, grading it XS, and also made early (on sight) repeats of Green Death and Edge Lane.
I wonder whether they did it to the cave, and Allen + Bancroft did the full line?
I've only got July/August 1976 of Mountain and unfortunately no mention of it in there.