Around 80 percent of students at the centre aiming for Kent and Essex grammar schools pass the 11-plus.
For Tiffin School, a student is expected to be naturally two years ahead of their peers, said a Kip McGrath Wandsworth representative.
Attending a creative writing class and completing a 30-minute homework task once a week can see pupils go from being average KS2 writers to writing at KS3/GCSE level, says founder of Crystal Tuition Richard Gray.
The 11 plus exam has spurned a massive industry – there are mock exam centres, endless study aids and an immense tutoring sector. Almost all of this is unregulated, so how do you choose?
Where: A number of centres located throughout the country.
Number of children per class: 6 children (At the Nine Elms centre, in central London)
Where: Harrow (near Harrow on the Hill Tube)
Number of children per class: 16