Thinking ahead for my daughter who is in yr 4 as to where she would go for secondary - she is v sporty - bright, does well above the average at her prep - I will be touring the usual suspects for her near where we live Francis Holland/ Putney High / Wimbledon High / Godolphin Latymer - I would prefer a day school although she has started muttering about boarding (others in class are following older sisters) - but people have suggested that all girls school generally in London don't take the sport side as seriously as they should and that either boarding or a mixed school (like Latymer) are better the latter because of the tradition of sport in boys schools - i wondered if this was a fair reflection of others experience??
Tbh the really sporty girls do sport outside school. And indeed the frustration can be that school sport can conflict with Club commitments.
A good sports person will probably want to specialise at around 13. If you have any idea what sport your child may want to focus on it might then be worth looking at Clubs. Great hockey Club in Wimbledon - mixed so a chance for older girls to socialise with sporty girls and boys from other schools. Putney, G&L and Latymer Upper are all close to the river so good for rowing. NHEHS, LEH and Latymer Upper host top level Club swimming, the latter accessible to girls from G&L. (The latter should also have rebuilt their sports facilities, including a brand new 6 lane pool, in time for your daughter's arrival.) Surbiton High is the place for gymnastics.
In terms of school sports, all the schools have teams and they play each other. A lot depends on the teacher/coach available. Some schools have good well-coached senior teams but appoint non specialists to coach the younger years. Some schools have more of a culture of encouraging participation, others will select the more experienced players from the start. (The latter in my view is important especially for those schools with a large state school intake, without a background in playing trad team sports. A school that encourages wider participation at the start is more likely to build a good cohort of sporty girls as the year group moves up through the school.)
West Londoners have a good choice in schools. There is no substitute for looking at each. Your daughter should then have a sense of whether she wants large and busy, perhaps with boys, or smaller quieter and nurturing.