The design life of the linings and pads is probably a mere 30,000 miles or 3 years. If they have truly survived 33,000 miles I would say that you have been lucky that they have never come adrift while you were driving.
As for your MOT tester I would suggest you get a new one. None of ours would simply give you an advisory for binding brakes, and what about the brake test itself? Did they really put your car on the rolling road tester? If so then their equipment or the testers judgement is fundamentally flawed.
I am frankly surprised that you have never thought to replace them, regardless of condition, for 18 years. just how much longer would you have been prepared to leave them if this had not occurred I wonder?