Very many pupils in independent secondary schools have attended state primary schools, but the mix varies enormously between schools (from under 1% to over 80%). For parents, the good news is that the majority of secondary Heads see no problem in this transfer − indeed many are more positive.
And the bad news? Very little, but parents need to make sure their child is prepared for the appropriate entrance exam, particularly if it is a highly selective school. There may be some transitional problems: they may not have picked up a language (in contrast to pupils from independent junior schools); or, if they move at 16, they may find their GCSE course does not adequately prepared them for an AS-level course in science or maths. But this type of setback should prove no real barrier to those prepared to work hard.