so your 3rd level schoolmaster has never been competed before age 19 and is spookey and not been exposed to much? Then he definitely isnt a schoolmaster and he probably isnt a 3rd level horse, just because some random from a riding school has told you that they have taught it to shoulder in does not mean the horse has been taught to sholder in, more then likely it has been taught to go crooked instead.
Medium is the UK equivalent of 3rd level. Stan had a wicked buck in him and would evade with the best off them, he did changes for fun but ask him to go sideways and he'd do his best to evade. Putting my brother on him was a risk but a calculated one (that and according to my brother he bounces well so a fall wouldnt have been that bad, better then putting him on an extremely explosive arab).
A friends Para horse made me look like a grand prix rider, I am most deffinatly not more than medium level!
Considering I have proof he was trained to Third Level...he was a lesson horse at Johnson and Wales...he was on the IDA team and I even contacted the head instructor there. So please don't just assume (yet again) you know my horse. I do consider him a schoolmaster because although he can be spooky at shows he's getting better as we go and he knows all the movements. At home we are great..he teaches me so much. It can just be tricky showing him. But it's a work in progress and as the last show proved to me, he's gotten much less spooky and although I don't completely trust him at shows, it's not a train wreck.
Again I fail to see what point you are making with your brother.