Going back 50 years, I used to use a large loose leaf book, the outer
being two thick black boards, the two joined by a pair of thick straps.
One outer had a key hole, the key being cranked, and operation of the
key caused the straps to be drawn into the cover. Pages had a special T
shaped cut out, which was arranged around the straps, the key operated
which tightened the straps, securing the book. Unwinding the key
released the straps, enabling new pages to be added or old ones
replaced.

What I can't remember is how the cut outs were formed in each sheet of
paper. Presumably something like a standard hole punch, but larger.

My Google-fu is having a day off. Any idea what that type of binder was
called?
--
Graeme