Mike,
On your original photo you can see perhaps 5 span wise smudges just forward of the dotted red line on the engine. On your second photo you can see them again with three just forward of the registration letters. The problem is that the aircraft in the photos are too clean and so they show up less.
These straps were quite neatly done but for Concorde they were rather agricultural. As far as I remember only BA aircraft suffered this problem for the reasons stated before, but I am not surprised to see that Air france aircraft were also modified.