I knew you'd have it in one of your books mate
It is
Strandgren's cyclogiro, of 1933.
Noyade has control 
Don't worry mate! It's
butrick that's missed
skytrain's answer (#25980) in all the Acapella talk! It was the
SAI KZ-XI, which was originally posted by RR on page 175 (#3479).
What a day of repeats
!!