Questions are being asked about the huge growth in the number of school pupils in England who are said to have special educational needs.

The proportion of those said to have the most severe problems rose from 0.8% to 1.6% of all pupils in primary schools and from 1% to 2.5% in secondary schools over only eight years, from 1991 to 1999.

In a pamphlet published by the right-wing Centre for Policy Studies, a former adviser to the last Conservative government, John Marks, suggests that this "extraordinary growth" is because pupils are not being taught properly.

But the Department for Education and special needs experts say it is simply that pupils' needs are now being identified in a way that they were not in the past.

In his pamphlet, Dr Marks says the proportion of pupils with less severe special needs also rose very rapidly from 1995 to 1999 - from 11.6% to 19.2% of pupils in primary schools and from 9.6% to 16.5% in secondary schools.

Call for an inquiry

Dr Marks calls for an inquiry "to establish accurately the scale of special educational needs and the use - or misuse - of resources".

A spokeswoman for the Department for Education said the increase in the numbers was accounted for by more children being identified as needing help with their education.

For example, pupils were far more likely now to be identified as having dyslexia - although many who do would say that schools often still do not recognise the problem.

There is no suspicion in official minds that schools are claiming to have pupils with special needs in order to get extra funding.

That would be triggered only at the fifth, highest level of need - when pupils are "statemented", as the jargon has it. And those cases are subject to independent external assessment.

And there is no gain to a school's standing in the league tables if it registers large numbers of pupils as having special needs - their test and exam results are counted alongside everybody else's.

'Additional' needs

The current figures coincide with what the 1978 Warnock Report on the subject said were the proportions of children with special needs, according to Glenys Fox, a member of the government's National Advisory Group on Special Educational Needs.

She stressed that the term covers a very wide range of "need".

"It includes children who might have only a very transient difficulty - for instance, glue ear when they are a young child, which perhaps limits their progress for a time but they catch up afterwards," she said.

"In a way it's not helpful to think of there being a cut-off point, because all children have educational needs and it's just that some children have more educational support needs than others.

"Now we are thinking more of children having additional educational needs rather than special educational needs.

"Children who are very able have additional educational needs which schools and parents want to see met.

"You might have a child with a particular aptitude - musical or mathematical. They might have additional needs to achieve their potential."

Better teaching

Mrs Fox, principal educational psychologist with Poole local education authority, said teachers were getting better at identifying need and teaching across a range of abilities, perhaps with the help of classroom assistants.

The literacy hour and daily maths lesson in primary schools showed this could work, she said - delivering the same sort of material but at the right level for each child.

Although there is greater awareness of the issue, she does not think the numbers deemed to have "additional needs" will grow.

They might even decrease if medical advances such as genome mapping prevent disabilities.

"Dyslexia might be a thing of the past because if you have got really good voice recognition software if might not be necessary to spell or write quickly," she said.

There is a code of practice for schools to follow in assessing children at each stage of the five-stage process of severity of special educational needs.

A revised code is to be introduced in September next year, following the government's Excellence for All Children consultation paper.

The new code will encourage schools to give children assistance at an early stage, and seek to involve parents more in helping them.

New legislation on special needs has been delayed due to the pressure on business in Parliament.