if your child goes there, why not make an appointment with the head to discuss this, rather than rely on anecdotal evidence? Results can vary for a huge number of reasons. If results have been pretty static in previous years, I'd put it down to cohort but it's difficult to know until next year's results are published.
Go and meet with the head, I'm sure it will be beneficial.
Edited to add: their website says this: 'Our results in 2015 saw our highest yet offer of scholarships across both Year 6 and Year 8: 41 in total! Eighteen Academic, sixteen Sport, three Art, three Music and one Drama.'
I haven't done any comparisons but this seems pretty good.