Examples of concrete help mum teacher has given can be found here:
www.mumsnet.com/Talk/primary/1640557-3-4-5-7-support-thread-2013
And here :
www.mumsnet.com/Talk/primary/1552850-Private-girls-schools-North-London
And there are others but I can't be bothered to look for them.
I know her IRL, about to out myself at least to her I think - my daughter was at a very laid back nursery that, in retrospect, she was bored at - she started going to mumteacher only two months before the 4+, when some of her basic skills were way behind average for her age. I have no doubt that she wouldn't have got into her current school without the help, which was friendly and supportive and not pushy. FWIW after meeting my daughter for the first time she offered, if I didn't want to do formal tutoring, to speak to me on the phone on a weekly basis and give advice - for free.
Yes, she makes a living out of tutoring and yes, I'm sure she gets lots of business from mumsnet, but she gives out a lot of free advice too, which is spot on.
These very selective schools largely take kids who have been tutored in one way or another, either by going to a feeder preschool like HHS, Broadhurst etc , or by going to a tutor, or by having very keen parents who put in a lot of effort at home. As has been said upthread, just rocking up unprepared will get you a "thanks but no thanks" letter, however much they say that they can spot a bright but unpolished child.
No one wants to tutor their young child, but elsewhere on mumsnet there are plenty of people who have found God in order to get their child into the state school of their choice. You have to work within the system you are in. The thing I like about her classes is that the stuff she teaches is stuff your child needs to know anyway - reading, writing, drawing, logic, basic maths. Yes, it's being done early, but it's got to be done at some point.
I don't want to derail the thread, but thought it would be useful to comment as someone who knows the system but has no financial interest in it.