The roof panel has two dents in total. This one, of 4cm width, is the largest.
I can live with that.
This is the front portion of the panel, showing one of the four footman loops spaced evenly along the very front. Keith has advised these are used to attach canvas covers to each window, to allow them to be fully opened without reflecting sunlight to aircraft etc. I will look into making a set of these covers, if reference photo/s become available. I have never seen these anywhere.
These are the two original brass wing nuts that tighten the steel angle piece(with two hand holds) shown in following 2 photos. Note the extra long wings, for ease of tightening.
This is the underneath side of the steel piece that the canvas would have been held to. You can still see the remnants of the canvas, the rivets that hold it, and the thin steel strip that sandwiches the canvas between the two parts. You can also see what's left of a rubber strip that sat directly forward of the canvas, making a 'waterproof' seal. That strip is approx 30mm wide (1+1/4" ish)
This is the same length of angle steel, seen from what would have been the rear side once locked into place by the two brass wing nuts. To the right of the hand hold, you can see the slotted hole for the wing nut, with a recess to match the shape of the rear of the wing nut. It would be impossible for it to slip out of place once nut was tightened. It took me a good 10-15min to remove the brass wing nuts, due to light rust on the thread. That's why there is oil visible around the hole. I knew if I broke either/both of the wing nuts, I wouldn't be able to replace them.