Many thanks David, sorry for the long delay but I've not had a chance to look at things since my original post.
This certainly seems to be the problem as the window is too high to close inside the hood - nothing to do with the hood adjustment.
At the moment I can't fathom out how to get the window back down past the stop in order to replace it!
I think the single bolt in the circled hole is the one, but I'm reluctant to start slackening of anything until I'm certain.
Any guidance would be most welcome.
Mike