The mansion, and the 120 acres surrounding it in Sindlesham, has been sold for millions to wealthy educationalists from South Africa and Australia.

The premises will reopen in September as Reddam House Bearwood.

It will be the 27th educational establishment in the growing Reddam House school chain and the first of three in England.

The owners intend to recruit the UK’s top teachers in every field to ensure the new co-educational, non-denominational school will be among the finest in Britain.

Initially there will be 60 child boarders at the new school which plans to increase the number of students from 440 to more than 1,000.

Pupils will be able to attend from the age of three months to 18 years old – and pregnant mums are already applying to secure places for their unborn children.

Registrar Sally Russell said: “We want every child to reach his or her potential. The Reddam House brand will be as famous as Eton or any other top British private school.” She added: “There will be effectively three schools on one site for the various age groups.

“Reddam House has a fantastic reputation in South Africa and Australia. The owners are investors in high-quality education and technology and want to be recognised as the best.” The Bearwood Mansion, once an orphanage and wartime burns unit for injured servicemen and women, has fabulous grounds, a chapel, man-made lake, swimming pool, and 350-seat theatre opened by The Queen.

Several new facilities are being introduced.

They include a new hockey pitch; a facelift for the theatre; a new sixth-form centre, individual study rooms and work stations, and areas for recreation and socialising.

Tammy Howard, head of the early learning school and junior school, said: “Reddam House will be the flagship school in the UK. The classrooms are huge. We will never need shoehorns to squeeze anyone in.” As the former head of Waverley School, she saw it climb into the top ten-rated national prep schools.

Dr Stephen Spurr, a former headmaster of Westminster School, was appointed managing director of Reddam House Europe last October.

He said the school will teach the national curriculum ‘and beyond’ and will produce the sports stars of tomorrow, adding: “Everything about the new school will be of the very best quality.” The new head will be Toby Mullins, a former chairman of the Society of Heads (2009-10) and chairman of the Independent Schools Council in 2011.

Ms Howard said: “Our Open Day on Saturday was exceptionally busy and we enjoyed meeting parents with an interest in all three of our schools. It is clear that families are excited about the Reddam House philosophy and the refurbishment and site developments taking place.

“With model classrooms in all areas of the school, parents were happy to see the state of the art learning environments the Reddam House team is creating.

“Graeme Crawford, founder of the Reddam House Schools was on hand with Dr Spurr to meet parents and share the exciting vision for the Reddam House Bearwood Community. We’re looking forward to hosting some more information sessions centred around the needs of families in each of the three schools and will be sharing details of these senior, junior and ELS events soon.”