If my detective work is correct, this is how the writing surface will sit when closed...
Attachment 430662
and with the supports extended....
Attachment 430663
and where the writing surface will sit when open...
Attachment 430664
Im guessing that the ‘awkward’ position when closed was secondary to the desirable flat continuous surface when open?
I have also found a feint pencil line which seems to have been scribed to locate the stop block which, in turn, puts the writing surface at its jaunty angle.