Have you ever heard of the signs in boarding house windows of yore that read "No Blacks, No Dogs, No Irish"?
If you're the child of immigrants with an obviously foreign surname that announces you're from a specific, despised immigrant group, or your skin colour isn't what might be called traditionally Anglo Saxon, you tend to have less sanguine ideas about your chances or your children's chances of non academic forms of intelligence getting them ahead in the UK.
The idea that you'll find your place and do ok is one that comes from a place of privilege, both class-based and educational.
There are lots of people who are ready and willing to tell you what your place is and keep you firmly in it if you're not what they consider a traditionally British person.
My friends who arrived in the UK in the 80s and had children in the 90s and beyond didn't find things had changed all that much from the era of the boarding house signs.
The RC community in NI, which found itself discriminated against in significant ways, responded by focusing on education and sending children to university. Even today, working glass protestant boys have the lowest level of academic attainment in NI. It is simply not possible that these boys all have a different form of non-academic intelligence. The culture of a community matters, and its level of engagement with the education system too.
The idea that there are separate forms of intelligence only feeds the very quaint notion that the power elite of the UK have a God-given right to be where they are and do what they do by dint of their special academic intelligence. Regardless of how often it's claimed that all the different forms of intelligence are equal, the fact remains that certain forms seem to result in being funneled into certain schools and universities and on to certain careers.
They happen to be the careers where capital and power are concentrated. You don't have to be an immigrant to be concerned about the almost complete exclusion of people from backgrounds outside of the traditional prep-public/ grammar/ independent-route into law, finance, medicine, and the upper echelons of politics. As seen here, it's something that has gone unnoticed, but it's the 800lb gorilla in the room.
There are very few people who are so thick that they couldn't do well academically if pushed and encouraged and properly taught. Giving up on children shouldn't be an option. It happens across the board in English schools, beginning with setting in primary schools.
I am saying that unless you occupy a place of considerable privilege in the UK, you should be actively focusing your child's attention on their academic performance and doing whatever it takes to keep your child from becoming one of the huge number of academic casualties the system as currently constituted is designed to create.