This is taken from the Sutton Trust's website March 2015:-
State secondary schools in England are not doing enough to stretch the most able students, Ofsted says.
A report from the education watchdog says gifted pupils are not keeping up with their clever counterparts in independent and grammar schools.
Children are not “realising their early promise”, says Sean Harford, Ofsted’s national director of schools.
Sir Peter Lampl, chairman of the Sutton Trust education charity, said the report “demonstrates an urgent need for more dedicated provision for the highly able in state schools”.
“Our research shows that England compares poorly with other countries in its provision for the highly able and our brightest students are failing to make the most of their talents,” he said.
Sutton Trust welcomes commitment to widen access to grammar schools
From 2010
TOP COMPREHENSIVES MORE SOCIALLY SELECTIVE THAN GRAMMAR SCHOOLS
So it looks like The Sutton Trust isn't against grammar schools as a way of educating the brightest, so long as a system like that used in Birmingham is in place, to open access to more disadvantaged pupils.