Tinribs
This is an example of the Air Traffic Control photograph taken at Gibraltar to which I think you refer. The photograph has a clock in the top left hand corner, and has date in the bottom left. This particular photograph was taken on my departure, in July 1974. I also have the arrival photograph.
The bold, nearly horizontal, white line is the line beyond which RAF aircraft were not supposed to cross, in this case, below it.
On the enlargement, I have tried to outline part of the coast of Spain, in red. The blue line is the approximate alignment of runway 27 at Gibraltar. The dotted, curving, line is the radar return of the departing aircraft.
At that time, Gibraltar ATC routinely forwarded copies of the arriving and departure photographs to the OC of the squadron concerned. ATC were at pains to point out in the accompanying letter that the arrival and departure were ‘without infringement’.