For families with the means, the choice between an academically selective independent school and a state grammar is a real trade-off rather than a clear hierarchy.
The short answer
On academic outcomes: top grammars routinely outperform top independents on raw measures (P8, value-added, Oxbridge entry per cohort). The grammar peer group is more academically uniform.
The longer answer
On wider provision: independents typically offer more sport, more music, more drama, smaller class sizes, and more pastoral attention. The fees fund a different kind of educational experience.
On cost: a state grammar is free; a leading independent is £20,000 to £45,000 per year, plus extras. Across seven years to A-level, that is £140,000 to £315,000 per child.
What experienced parents do
The decision often comes down to what kind of community you want for the child. A grammar peer group is academically tight but socio-economically narrow within a region. An independent peer group is academically broader but socio-economically narrower nationally.
What to avoid
Avoid: the assumption that "independent must be better because it costs more". The relationship between cost and educational outcome is not linear; many state grammars deliver outcomes that independents matching their fees would envy.
Practical next step
Sit both routes if the child can. A grammar offer plus an independent offer leaves the family with the genuine choice. Foreclosing one route on principle reduces options unnecessarily. A small, deliberate action this week is worth more than a grand plan for the year ahead.