Revelations of historic abuse have been "shaming" for everyone involved in running boarding schools, according to a leading headmaster.
Ray McGovern, chairman of the Boarding Schools Association (BSA), said such incidents had "cast a long shadow" but that today's boarding schools a re unrecognisable from those operating in the 1950s, 60s and 70s and should not be judged on their predecessors.
In his speech to the BSA's annual conference in Glasgow, Mr McGovern, who is headmaster of St George's School, a state day and boarding school in Hertfordshire, is expected to say he is "unreservedly sorry" that such abuse had been allowed to occur.
He says: "I have been chairman of the BSA in a year when we have been reminded forcibly of times in the past when not everyone working in boarding was there in the best interests of the children they were supposed to serve and protect.
"All of us are shocked when evidence of abuse comes to light, and there is no doubt that revelations of historic abuse cast a long shadow over today's schools. It shames me, and it shames the sector, that behaviour such as this happened or was allowed to happen, and for that I am unreservedly sorry. I am sorry to those who were affected directly and to those who placed their trust in individuals who could not be trusted.
"However, boarding schools in the 21st century are, in terms of safeguarding and student welfare, unrecognisable from the institutions of the 1950s, or 1960s, or even the 1970s. If boarding schools then were closed worlds, in which power was unequal and concern for the school's reputation took precedence over the welfare of a child, none of this is now true."
Mr McGovern is due to say that apart from legislation, regulation and inspection processes, everyone in the BSA shares a "genuinely different attitude" to caring for children.
"Let parents and inspectors and journalists and TV cameras come into any of our schools and see the difference: see the ethos of genuine concern for the children in our care," he says.
"Today's boarding schools should not be judged by their predecessors of generations past. You wouldn't judge a hospital now on the basis of how it was in the 1960s.
"Whilst no one would condone any behaviour that harmed or harms a child, it is important to remember that as a society we have changed in our expectations of how children are listened to and treated. Gone are the Victorian views of 'seen and not heard', gone are the days when 'sparing the rod' was considered a weakness likely to spoil a child.
"In the trauma and anxiety of dealing with such cases it is important to remember that these circumstances were not of our making. The responsibility lies squarely with the individual responsible."
His comments come months after a former head teacher at the prep school attended by Deputy Prime Minister Nick Clegg was sentenced to eight years in prison for abuse.
Roland Peter Wright, 83, who taught at Caldicott Boys' Preparatory School, a day and boarding school in Farnham Royal, Buckinghamshire, assaulted five pupils aged between eight and 13 between 1959 and 1970. Two other fellow former teachers, John Addrison and Hugh Henry, pleaded guilty to sex abuse.
In his speech, Mr McGovern also hits out at claims that boarding school pupils are not well prepared for real life.
"We supply a steady stream of highly motivated, superbly qualified and completely colloquial students to the best departments of the best universities. Some people say that boarders can't boil an egg or wash their own clothes. This is not my experience. I expect it's not yours."
He adds: " Universities - and indeed employers - increasingly look for more than top academic grades. They look for social skills and confidence, independence and resilience, character and perseverance. They look for true grit. You want all that as well outstanding exam results? No problem. That's what we do. Many would say that's what we do best; in state and independent boarding schools."