A dwindling number of pupils at one of Norwich's biggest schools has left it with a budget deficit of more than £400,000, it has emerged.

Ten years ago, the Hewett School had 1,500 pupils on its books, but that number has dropped dramatically, with just 734 children enrolled at the Cecil Road secondary school as of September last year.

The average secondary school in Norfolk has between 950 to 1,000 pupils.

And, with funding for schools from the government based on the number of pupils being taught there, that has left the Hewett facing a £430,000 deficit.

That deficit was £600,000 last year and school leaders said they have already taken action to reduce it, such as not replacing staff who have left.

School leaders have reassured parents that education of children will not suffer. They say governors have a three-year plan to remove the deficit.

And they still aim to move from the current 'good' rating from inspectors Ofsted to 'excellent'.

To tackle the deficit further, the school will have to make changes to its leadership and management structure, with posts at risk, while fewer teachers will be needed given the number of pupils is down from 864 in September 2012.

Rob Anthony, associate headteacher at the Hewett School said: 'The Hewett School has a budget deficit which was caused by a falling number of secondary age pupils in Norwich over a nine year period.

'From 2016 the demand for places will rise quickly and we expect to take in more students from all parts of the city.

'The governors are working to a three year plan to remove the deficit gradually so as to protect the high achievements of students.

'As part of the plan, leadership and management posts at the school will be restructured, but this will not prevent us moving from an Ofsted grade which is good to one which is outstanding. All teachers may apply for one of the new responsibilities.'

And the number of teachers will be reduced because there are less pupils to teach.

Mr Anthony said: 'As a result of changes to the number of students on roll in the 2014-2015 academic year, the school also anticipates the need for fewer teachers. This is a normal process. The school expects that adjustments can be made through the usual staff turnover.

'Each year, all schools have to alter the number of teaching staff up or down to remain within their allocated budget and to continue to provide high-quality education.'

A spokeswoman for Norfolk County Council acknowledged there had been a 'trend of late of falling pupil numbers' in secondary schools, but that the county was coming out of that phase and pupil numbers in secondary schools would start to rise.

The Hewett School is a Foundation Trust School and part of the Central Norwich Foundation Trust. The school and its governors are responsible for its budget.

But the council spokeswoman said: 'However, when a school has a deficit budget, and as is true in the case of The Hewett School, we work with closely with the headteacher and governors to help them plan how they are going to bring their finances back into balance over two or three years, while still delivering a strong academic performance.

'It is the county council's priority to ensure every Norfolk child and young person has access to a good school, and we are doing all we can to help The Hewett School get back on track.'

• Do you have a story about your school - or are you a parent with a child at the Hewett who has a view on this story? Call reporter Martin George on 01603 772468 or email martin.george@archant,co.uk