Andy Burns wrote :
Normally just frame fixings straight through the, erm frame, into the
masonry, can you see evidence of them on any openers?

My bathroom's smallish window, the opening half, has seven such frame
fixings visible. So likely the entire window has fourteen fixings
around it.

The usual way to get the windows out, is to use an electric saw to feel
for and cut through the bolts, once cut, the entire window comes out in
one piece.

Wooden frames are usually removed by sawing them into sections in
place, plus cropping any fixings.