Parents in some authorities are up to 50 times more likely to start a legal battle with their local council over special needs provision for their children than others.
A TES analysis reveals that the London borough of Richmond had the highest rate of special needs appeals of England's 150 local authorities with more than 10 for every thousand special needs children in 20045. Warrington and Coventry councils had rates 50 times lower, with just 0.2 appeals for every thousand SEN pupils.
The news follows a government warning to local councils that some are breaking the law over special needs assessments and statements, and calls from lawyers and parents' groups for the system to be tightened up.
John Wright, of the Independent Panel for Special Education Advice (IPSEA), said higher concentrations of articulate and resourceful parents, prepared to challenge their authority, could be a factor. But he said: "If all authorities followed their duties according to the law there probably wouldn't be this huge variation."
Julia Thomas, Children's Legal Centre senior education solicitor, said low appeals figures might be misleading as they might be down to authorities failing to inform parents of their right to appeal.
In November, the Department for Education and Skills wrote to all local authorities saying that some were illegally operating blanket statementing policies and not specifying the provision individual pupils were entitled to.
Last month MPs were told by the Law Society, Children's Legal Centre and IPSEA that some councils deliberately made vague statements of need.
Mr Wright said he had far more calls about Essex than any other authority.
Ms Thomas said the Conservative-run authority broke the law on statements most of the time.
Douglas Carswell, MP for Harwich and Clacton and a member of the committee, claimed Essex tended to wriggle out of providing for SEN pupils.
But although the Special Educational Needs and Disability Tribunal's annual report shows that the county had the third-highest number of appeals in 20045, it finished only 21st in the TES table.
This was compiled by comparing the number of appeals registered with the tribunal against government figures showing the number of special needs pupils, both with and without statements, in each authority. It means a council's ranking is unaffected by its size or a particularly high concentration of SEN pupils. Nationally, the tribunal's report showed a 4.1 per cent drop in appeals in 20045 compared to the previous year with 26 per cent of cases relating to girls and 74 per cent to boys.
A refusal to assess a pupil's needs was the biggest reason, accounting for nearly four out of 10 appeals, while autism was the largest type of need at 24 per cent of cases.
A fifth of appeals were conceded by local authorities and 45 per cent withdrawn. Of the remaining 36 per cent where decisions were issued, more than three-quarters were won by parents.
An Essex council spokeswoman said it had received a good Ofsted rating for its SEN provision. It was the second-largest county and had a number of very articulate parents arguing their case.
A Richmond council spokesman said it was committed to further reducing appeals, which had already dropped from 39 in 200304. He thought the level was connected to the number of parents with high expectations in the borough, which Ofsted said had good special-needs provision.
Additional research by Richard Reynolds