I wonder if this was supposed to be the ghost of the servant girl that was mentioned earlier in the slideshow. I don't think that it could be Angelique, as I think that she would have been identified as such in the script, if not on film.
Very shortly an answer to that will be coming in a scene in the script that only appears in the 129 minute version of the film.
And before we get back to the script, I want to share the following candid production still that I made reference to back when we were dealing with Scene 69(the picnic). It's of David Selby, Kate Jackson and John Karlen taking a break from shooting the scenes at the greenhouse:
And one of the interesting things about what Karlen is doing is that he had never ridden a bicycle before he did so for the scenes for NoDS, so he practiced a lot before shooting so he wouldn't look ridiculous. Of course, if the film had been shot today, they could have just put training wheels on the bike and then taken them out in post.
But that sort of technology wasn't available back in 1971.