i asked a similar question on the primary school section- you might want to look at the answers - it not that far down the page - dont know how to send a link I'm afraid!
from my research i would say of those i am looking at Notting Hill and Ealing and Latymer are good choices - the latter is pretty hard to get into I'm told but is my preferred choice. I've also heard good things about Godolphin and St Pauls but they are pretty top notch academically so depends on how bright - and prepared - your daughter is
I have rejected St James, Harrodian, Ibstock Place.
LEH and Putney High bit far for us but pretty good i think
Its very hard to cut through all the gossip and prejudice and find out what these schools are really like. I think the top ranking ones are consistently good if you're looking for that sort of thng but they are hard to get into and the next level down of school is much more variable
I know this may be a little late but I was searching for entrance exam papers online and I came across several mumsnet threads about secondary schools and as I, and most of my yeargroup, absolutely ADORED Godolphin and Latymer I thought it would be important to let all of you know. It may not produce the same insane Oxbridge entry results as St Pauls Girls but it has phenomenal pastoral care and gets all girls into really good universities: girls who at other schools would never achieve those sorts of successes. It does get about 17% of the year into Oxbridge, about 5% into Ivy League Schools (that is to say only 5% go to US universities and all go to Ivy League Schools!) and the rest go to Bristol, Edinburgh, Durham, Nottingham, Manchester, UCL, LSE or Leeds. It was very sociable and friendly, in a way that I didn't find more high pressurised schools like SGPS and yet got better results than schools like Francis Holland. I can really tell that someone went there as it gives you self assurance but not overconfidence and it definitely does not make you always need to prove that you are academic (unlike SGPS...). I really, really loved it and I think most girls you'll meet from there would agree, unlike at many other London girls schools.
Also it came top in the country for IB, has incredible school trips (Sinai desert anyone?!), great facilities (e.g. hockey pitch onsite) and brilliant teachers.
I really cannot reiterate how much I loved it. Also if your daughter is thinking of leaving in 6th form, I would urge her to stay as I think it makes a big difference having teachers who have known you since you were 11 writing your references rather than people who have only seen one year's worth of work from you...