No one knows better than the Royal Wanstead Children's Foundation, a charity that supports children at boarding schools, how careful you need to be.
Over the past 35 years the fund has put 1,600 children through 100 schools, and is currently supporting 250 secondary pupils.
"Most of our children have one or no parents, and have a deep need for a home away from home," says chairman Colin Morrison. "Often they're only a postcode away from being in care."
Going away to school can keep a child's home together, he says. "But for it to work, children need to know that life back at home is as stable and predictable as it can be. There needs to be, to some degree, an accepting of authority and structure, and they need to be enthusiastic."
Then there is the question of how many disadvantaged children a school can take, and how well it can handle them. Boarding schools such as Christ's Hospital in Horsham, West Sussex, and King Edward's, in Whitley, Surrey, take many vulnerable children. But as Mr Morrison says: "You don't want these children to be surrounded by the problems that they are trying to escape.
"This isn't a solution for all children, or all schools. It can be tough for a time. You just have to be patient. Yet some schools will expel a child with no sensitivity whatsoever to what they are going back to.
"And sometimes you'll hear a parent at speech day saying something like 'They shouldn't be taking on so many rough children' - the kind of parents who are happy to have the drug-crazed son of a pop star in the school, but not the equivalent child from an inner city."