The dark brown things are the inner most sections of wing leading edge, they are hinged to the spar along the top edge so that they can be rolled upwards for access during build and maintenance.
Visible in this report on Just Jane
https://www.dailymail.co.uk/news/art...FIX-model.html
Fantastic picture, I went there when they were building the ATP and tried to imagine what it was like in wartime, in fact it wasn't much different..