Running a multi-million pound hospital may not be child's play, but designing it was.

Health managers yesterday unveiled plans for a new children's hospital in Brighton and Hove and revealed young patients' ideas played a key part.

The 130-year-old Royal Alexandra Hospital for Sick Children in Dyke Road, Brighton, will be pulled down and replaced with a £36 million multi-storey unit at the Royal Sussex County Hospital in Eastern Road.

Project director Richard Glenn said: "We are all excited about how this project is coming together.

"We used a theatre company to get the children articulating their experience of the hospital, some of the things they were afraid of and some of the improvements they would look for.

"We have been able to talk to the families of those children and say, 'How can we take their comments and put them into the design?'"

The development will include 100 in-patient beds in a mix of single and four-bed units, three operating theatres, diagnostic and treatment facilities, including X-ray, and an intensive care unit.

There are also plans for a cancer care day centre, parent accommodation and children's play areas.

One of the most unusual cases to be seen at the Royal Alex in recent years was that of Annie Dudeney, whose parents have backed the plans.

She has Edward's syndrome, a condition affecting the heart, lungs and digestive system.

The illness is caused by an extra chromosome and affects about one baby in 5,000. Most do not make it to their first birthday.

Annie turns nine next month and is believed to be the second-eldest child in the country with the condition.

She is also one of the hospital's most regular visitors, needing treatment up to five times a year.

It was in the Nicholson Ward of the Royal Alex that Annie's adoptive mother Jane Dudeney, from Peacehaven, first set eyes on her. It was love at first sight.

She said: "Annie has heart problems. She can't walk or anything like that. But she can roll for England.

"She's a real minx - the staff here love her. This hospital is very special to us. The staff are fantastic and they have all known Annie all her life.

"They are like family. It's never a worry to come into hospital because you know they are going to do everything they can to make her better."

Jane has mixed feelings about the transfer.

Having lived years longer than expected, Annie's prognosis is poor and it is not clear that she will live to see the new hospital.

Even if Annie does further defy the odds by living another three years, it will be a wrench for her and Jane to leave such a welcoming environment.

But Jane knows the Royal Alex has its limitations.

She said: "When the children are very ill it would be nice to have your own room, not in the open ward and you have got that in the new hospital.

"For special needs children like Annie it is going to be fantastic."

Glamour model Jordan's 20-month-old son Harvey, who is blind and has a condition that may affect his growth, was born there and has ongoing treatment.

The model was reported to have taken Harvey to the Royal Alexandra in May after he stopped feeding and his temperature soared.

Jordan - real name Katie Price - told The Argus: "I'm pleased Harvey was treated at the Royal Alex. We were both treated very well and the staff were all fantastic.

"I hope the hospital does very well at its new site and that it continues to be a credit to Brighton."

Anna Jones, 43, from Patcham, whose daughter had extensive treatment for a life-threatening illness, said parking could be a problem at the new site.

But she added: "The Alex doesn't afford a lot of privacy on the wards, especially for a teenager. It is very old-fashioned, so we would welcome a modern facility."

The move to the Royal Sussex will be paid for through a government private finance initiative (PFI), with the new hospital expected to open in 2007.

Paediatric surgeon Varadarajan Kalidasan chaired the committee which began drawing up the plans five years ago.

He said: "The main drivers for this project have been clinical needs.

"As far back as ten to 12 years ago people realised you can't provide a sufficient service at the existing Alex. When we wanted to improve the care and increase the workload it proved very difficult, because the very structure of the building doesn't promote that.

"We have a major accident and emergency department at the Royal Sussex, which a lot of children go to, but we are across town.

"It also meant there were issues of safety for children.

"People in A&E may not always have paediatrics in mind. It's much better to have all these things under one roof."

Responsibility for delivering clinical and nursing services and educational needs will remain with Brighton and Sussex University Hospitals NHS Trust, while PFI contractors Kajima will provide the facilities and long-term building maintenance services.

The contract will last 30 years.

But Mr Kalidasan remains mindful of how PFI schemes have not always succeeded in the past and is stifling the celebrations until he is "absolutely sure" the job has been done.

He said: "I will be happy the day I actually see them digging the hole. There were moments during the last five years when things didn't look that good."

The Royal Alex says staff, patients and visitors are in favour of the move because the hospital was getting too cramped for comfort.

Paediatric nurse Jo Trussler said: "The biggest problem we have is space.

"We use every inch but we have very limited storage space and not enough space around beds for children's toys and parents to sit.

"A lot of the equipment is in the corridors and on the landings.

"The wards themselves are open wards, which means we can't always guarantee privacy. It is also very difficult to get children in with children of a similar age."

Sister Trussler, who has been at the hospital more than 20 years, said a survey of children and parents had showed managers they wanted the new hospital to have more home comforts and more space beside beds for parents - features which will be given priority in the new hospital.

She added: "I'm really looking forward to it. I'm very excited and feel privileged that I have been able to be a part of this."