Gnasher, I think you're talking bollox mate and I'm not being confrontational her, to answer your points:
every road has a limit and you drive to conditions too, why was this not one of them
whether he's on an advanced test or not, overtaking a P driver is not against the law and you wouldn't fail a test, you'd be more likely to fail it if you sat behind when an overtake was possible....given you don't break the limit. Saying that, I know certain examiners would let it go once instead of you sitting in a potential dangerous position (my examiner gave me the opportunity of following him outside a mile long line of standing traffic, otherwise the first hour of my test would've seen me sat in a queue
unless you're a slow moving wagon or learner on the motorway, most vehicles are surprised by someone doing 50 as its not expected, good observations are key to progressing but most people don't have that skill without taking further training. I still stand by my remarks about doing 50% of the speed in a given speed zone is dangerous if there's no other factors involved and its just down to a slow driver