You need
www.education.gov.uk/schools/performance/
to drill down into the results.
In particular, you need to look at what high, middle and low attainers achieve, and what percentage of the cohort they form.
DS / DD's comp has a 'headline' 5A* to C figure of between 80 and 90% every year. However, it is absolutely clear from the detail that this is because, despite being in an area with residual grammars, it has an unusually high proportion (nearly 50%) of high attainers, almost all of whom reach this benchmnark.
Which is fine for me, because I have 2 high attainers as children.
If I had low attainers, though, I would avoid the shool in favour of other locakl comprehensives - because there are very few low attainers in the school, and only 20% of them mnake the benchmark.
So 48% could be very good indeed: if the school is 80% low attainers and 45% of them make 5A to C that would be brilliant. But if it's 48% with 50% of the school being high attainers, that's terrible. The detail in the link really helps you to dig down and investigate, and helps you to identify what the school might be like for your child. I know a 'failing' comp, for example, with 100% 5A to C in genuine GCSEs for high attainers. the problem for their heradline figures is that they only for 5% of their intake, with midle attainers being anoter 10% and 85% being low attainers.....