Mary Warnock was the head of the inquiry which led to the 1981 Education Act. This transformed the teaching of thousands of children who were once dismissed as subnormal or maladjusted.
In an interview with The TES this week, the philosopher and former headteacher said that the inquiry had brought about revolutionary change.
But she called the introduction of statements of special education need, which the inquiry committee invented to protect severely- disabled children, disastrous.
"It is the greatest obstacle to good provision," the Baroness said. "There are far more children statemented than we ever envisaged. It has ceased to be about what the child needs and has just become a battle for resources."
The 79-year-old said she was also disappointed by huge amounts of money wasted on litigation over statements. "This is what has been so tragic.
It's a huge industry, it's wasteful and unproductive." In the interview, Baroness Warnock suggested the changes had left some children worse off than 25 years ago.
"We were so tremendously hooked on integration ... that this idea grew up that specialist schools would only serve the most disabled, which is more or less what happens now," she said.
"I think the children with mild learning difficulties who are now in mainstream schools have rather a rough time: they are often bullied, nobody really wants them and they often don't benefit from the education going on around them."
The Baroness said statementing should be abandoned as well as further moves towards inclusion. Instead there should be a broad look at how pupils'
social and educational needs could be met.
Her comments follow critical reports last year by the Office for Standards in Education and the Audit Commission, which said the statementing system was bureaucratic and wasted money needed to support vulnerable children.
A spokeswoman for the Department for Education and Skills said it was opposed to a major overhaul because it wanted to let recent changes settle.
However, the department plans to publish an SEN action programme in the autumn which it says will contain practical measures that will improve provision for pupils.
The Disability and Equality in Education group said it was disappointed by Baroness Warnock's comments because they seemed to oppose further inclusion.
Christine O'Mahony, the charity's training co-ordinator, said: "It is sad, really. Our experience is that children who are taken out of mainstream education often bitterly regret it and that it is one of the most hurtful things that has happened to them.
"Statementing is a tedious, lengthy and unpleasant process, but just the fact that the statementing system isn't working is not a good reason to say that inclusion isn't working."
"What a disaster we created" page 3, Special educational needs supplement in this week's TES