The thing is, for the genuine superselectives, there are often more than 15- 20 applications per place. And pretty much all of those kids are top of their class or working at greater depth and pretty capable. The cleverest won’t necessarily get the place. The ones who get the places are those who are BOTH very clever AND well-trained to manage the timing and type of Qs. You need both and certainly the latter to beat off the strong competition.
So the level of intelligence of a child is hard to measure (you could get them assessed with an IQ test or something similar) but that alone won’t be a guarantee.
In the superselectives in N.London, more families than you think are prepared to tutor from very early and suoervuse their kids through hours of prep per week for years. It’s hard to compete with if you’re not up for that. It’s not how it should be but is often a reality for superselectives places.
But, given they are often in affluent areas and the SS takes a tiny proportion; often the alternative schools are still very good with a full normal range of ability. It’s not like the high schools (secondary moderns) in fully selective areas where the top 30% are missing because they are all at the Grammars.
So yes, you could move to one of these areas and have a go. Hold lightly to the idea, because it’s hard to succeed. Be willing to go to one of the other local schools in the areas as you may well need to.
Alternatives, if you’re sure your DC is going to be in top 30% and you’re up for a moderate level of prep, is to go to a fully selective area like Bucks. All good if they pass…not so good if they don’t.
Better still, research areas with great Comps…move into the catchment making sure you’re pretty close and get a place there without need for prepping and exams. If you select right, you can be in a school with lots of able children who go into do extremely well.
Lots of people move OUT of grammar areas at this point and head towards the great Comps areas, to avoid the risks rather than move in to face the risk. If you need to move anyway, why go somewhere with further uncertainty and risk, when you could go somewhere which although not selective delivers a great education and results?