Christ's Hospital, the boarding school for children in need at Horsham, celebrates its 450th anniversary this year.

It is also the centenary of the school's move from London to its Sussex site.

Entering Christ's Hospital is like turning the clock back hundreds of years.

A winding road leads past sports fields to the imposing brick-built school set in 250 acres of rolling countryside.

Wandering around the manicured quadrangle are pupils clutching books who look as if they have stepped out of the 16th Century.

They wear the distinctive blue and yellow uniform which has changed little since the school was created in November 1552.

Both boys and girls wear the navy ankle-length Housey coat with a loose leather Brodie belt, white cotton shirt with white neck-band similar to those worn by barristers and bright yellow socks.

They are following a tradition started in 1552 by the young King Edward VI, who responded to an impassioned sermon on the needs of London's poor by setting up charitable institutions, including the school.

But the history of the school and the dignified way pupils drift about in their historical garb does not stop them behaving like modern teenagers.

Sixth-former Charlie Beringer remembers how one boy got into trouble for copying the Milk Tray advert by abseiling in his frock coat from the roof of one of the residential house blocks to deliver chocolates to his girlfriend on St Valentine's Day.

Christ's Hospital, given its name to emphasise hospitality, was founded in the old buildings of the Grey Friars in Newgate Street, London, to provide food, clothing, lodging and "a little learning for fatherless children and poor men's children".

Both boys and girls were taken in but were kept segregated.

The money was raised by the City of London, the Church, businesses and householders.

The boys' school moved out of London 100 years ago to Horsham because it was considered a healthier place for the children to live.

The girls went to a school in Hereford in 1778 but joined the boys in 1985.

The school is supported by the largest charitable foundation of its kind in the country. The proceeds of endowments and investments over the centuries enable the school to fulfil its original objective to provide education for children in need.

Today many of the 825 pupils come from deprived backgrounds. Forty per cent receive free education, other families pay on a sliding scale after being means-tested.

Only three per cent pay the full fee of £14,715 a year. Forty per cent come from London and about 30 per cent from Sussex.

The school takes in 120 youngsters annually and they all have to pass entrance assessment tests, based on the National Curriculum.

School spokeswoman Carol Blackwell said: "One of the criteria is need. It may be financial, the loss of a parent or sibling, ill-health in the family or a broken home.

"Here they thrive in a boarding school environment and still keep in touch with home. They get a good start in life which they may not have had otherwise."

Although it was a traditional school this did not mean it was stuck in the past. Nevertheless the pupils enjoyed the traditional aspect of their education.

Mrs Blackwell said: "Ten years ago they were offered the chance to modernise their uniform but they voted against it. They are very proud of it."

The pupils enjoy their traditions, particular the daily ritual of marching in their house groups into the baronial-style dining hall for meals to the accompaniment of the school band.

The school balances its traditions with more modern forward-thinking.

It is two years into a ten-year project spending £60 million refurbishing the living quarters, classrooms, the arts school and music facilities.

Christ's Hospital has 90 full-time teachers and several part-timers. One of the longest serving is German and French teacher Tom Jeffers, who joined the school in 1972.

He said: "When I first started there was less privacy, with boys sharing dormitories for 25. Now there are five to six in a room and the sixth-formers have single or double rooms.

"We take in some pretty bruised children who come from dysfunctional families. Their behaviour patterns can be very difficult to cope with.

"But children enjoy coming here and there are always tears when they leave. It is a huge wrench for them. The school gives them a sense of belonging and importance."

From earliest times one of the highest distinctions at the school is to be awarded academic buttons bearing the head of Edward VI.

The large silver buttons and velvet cuffs are the mark of sixth-formers known as Grecians, in their final years, demonstrating outstanding academic performance in more than one subject.

Grecian Mark Adams, 17, wears a coat which bristles with the special buttons.

His parents are in the RAF, which has involved the family travelling, making it difficult for him to form friendships.

He said: "Academically it is a lot of hard work but socially it is very good and we all support each other.

"I think the uniform is something to be proud of. I was a bit taken aback when I first arrived. But with 800 pupils wearing it, you soon get used to the tradition."

Headteacher Dr Peter Southern said the aim of the school was to continue with the tradition of giving the best educational opportunities to all.

He said: "We are heavily biased towards those who can't pay. That is why we are special.

"It is important we keep the same aims in our sights as those of 450 years ago, to take children from whatever backgrounds and give them a top-notch boarding education, irrespective of their ability to pay or any issues they may have at home.

"We give them a secure and safe environment where they can concentrate on doing well at school."

The school is planning a year of celebrations to mark its two anniversaries:

May 4: The school band parades through Horsham town centre.

June 4: Musicians from Christ's Hospital take part in the Golden Jubilee state procession from Buckingham Palace to St Paul's Cathedral.

June 29 to July 3: Centenary festival of music at the school.

September 20: St Matthew's Day service at St Sepulchre's Church, London, to mark the school's historic connections with the City of London.

March 17, 2003: A London musical performance at the Barbican, conducted by former pupil Sir Colin Davis, to commemorate the signing of the Royal Charter in 1553.