Being over-tall when young is due to over-feeding, just like being over-weight. So you get them to eat less.
In the red book, you can work out their predicted adult height, if that's 95th centile, then it's fine that they height and weight at 95th, they may just be the 1 child out of 20 (so just over one in a class) who should be that height. However, if mum and dad don't give a particularly tall adult height, then they may be over-tall, not 'just big and in proportion'.
This is what I mean by we have a screwed up ideas, we make excuses, 'people come in all shapes and sizes', 'they're active with it!', 'they're in proportion!'. Nowadays people are increasingly coming in the round shape, and morbid obese size, and it starts in childhood.
But parents get all uppity when society tries to do something about it. "How can I stop them growing?!"- this is the whole issue. How do we stop children in the developed world over-growing, while many in the world are malnourished.
Obese children are more likely to be taller than their peers, then they reach and early puberty, stop growing, and put on more weight, and stay obese as adults. I don't want that for my child, so I try not to remain blind to the dangers of being over-tall. There is no '11 year old size', but there is a normal range, but we are accepting more and more children at the top of that normal range, and labeling that as normal, having 5 children in a class of 25 above the 95th centile simply is not 'normal', yet we now think it is. If your child is outside the normal range for their age, then they may not 'just be big', or even 'just be small', something is going wrong. But it's hard to admit that, and start doing something about it.