Mairi, I don't know what the risen teardrop domey thing is at the top, but on the side of this fairing, as far as I remember, you have channels, or tracks that a sticky outy thing on the ends and sides of the flaps run in. Inside the big fairing is a very large broom handle metal thing (screwjack) with a thick thread on it. This turns rapidly, and a large nut thing attached to the flap runs up and down it the screwjack. This makes the flaps move backwards and forwards, and the channel in the side of the fairing, into which the end of the flap thing runs, curves, making the flaps angle downwards according to how far they run along the screwjack. I don't recall a panel there because the flap would scrunch it. I think you saw the channel and it was meant to do that.
Now BOAC has been flying the beast for far longer than me, so I now hand over to him, he heap smart.............