David, Having flown both SEP and RAF jets in my time (and now mainly helicopters), I would say that the Cessna pilot didn't have as good a chance of seeing you as did the jet pilot. A Cessna pilot's wing is above him and he sits on the left of the cockpit. If you think about the geometry of that, you might understand. The fast jet pilot, on the other hand, has a much better field of view.
It's a strange thing that where two powered side-by-side seating aircraft are concerned (I appreciate that you are flying a glider and therefore have ROW irrespective) the one with the other on it's right must give way, whilst the one with the other on its left must hold a steady course.
Therefore, the one who is least likely to see the other aircraft must give way. The one who is more likely to have seen the other one must initially allow the "blind" pilot to take the avoidance on him, meanwhile thinking: "Well has he seen me or not?"
From my own routine daily encounters with such aircraft, probably not!
