This from Councillor Caroline Patmore, portfolio holder for Children's Services, North Yorkshire County Council, 17 June, 2009 (link, p2):
The number and nature of parental appeals to the SEN & Disability Tribunal has remained stable over the past 3 years, with 27 appeals lodged in the 2007/8 school year. In line with National Statistics, the majority (74%) of these appeals were against the Local Authority’s decision not to carry out a statutory assessment of pupil’s special educational needs. Only 12 of the lodged appeals proceeded to a final hearing, as mediation with parents led to the majority of appeals being withdrawn. North Yorkshire remains below the national average in the number of appeals lodged.
Early indications from the statistics for this year indicate that there could be a reduction in the number of appeals lodged, with only 10 lodged so far to date.
 Ms Patmore is referring to the period 2005 - 2007 (average no of appeals 27.6). The number of appeals almost doubled from the previous three year period 2002-2004 (average number 15). It is more informative to look at the trend from 2004, following North Yorkshire's Big Bang in 2003 (clue: up, up, up). See here and here for more analysis.
 SENDIST annual report (p3) 2008-09: the average number of appeals against refusal to assess was 36%, more or less the same in 2006-07 (40%) and 2007-08 (37%). North Yorkshire's was 74%. So not quite in line. Why was North Yorkshire's figure so high?
 SENDIST doesn't provide much data down to local authority level, so we don't know how many appeals were won or lost by North Yorkshire. We do know that local authorities lost 71% of appeals against refusal to assess that year, so based on that figure - admittedly crude - North Yorkshire would have lost 14 appeals. It was in their interest to concede, rather than have judgements go against them.
 SENDIST stopped publishing figures for number of appeals per 10,000 of school population in 2007, but figures from 2006 and 2007 do show North Yorkshire's to be lower than the national average (3.08 v 4.50 for 2007). There is no clear reason why. Given Ms Patmore's interpretation of the figures up to this point though, it would be nice to see the hard data before awarding points.
 Total number of appeals in 2008-09 turned out to be 17, which was down on the previous year. However, one year's data compared to another isn't really informative -the figures for 2009-10 went back up to 22.
The Lamb Report, published on 16 December 2009, which looked into parental confidence in the SEN system, said:
5.80 It is better for everyone if provision is made for children without recourse to the Tribunal. However, the cases going to a hearing are becoming more complex and issues under contention are more likely to be matters of law to be decided, rather than matters of fact to be established. Despite changes in the Tribunal system, many parents are finding appeals too difficult and complex and feel unable to pursue their claim without legal support. This leaves only those with considerable personal and financial resources able to afford representation.
5.81 With increasing complexity and in the interests of equity legal aid should be available for parents attending a Tribunal hearing. This is a matter with direct consequences for parental confidence. However, subject to financial qualification, there is already provision, for ‘exceptional funding’ where a case meets a criterion of overwhelming importance to the client or a threshold for complexity. This scheme has been little used, is not well publicised and the procedures for accessing the funding are reported as being slow and complex.
In the author's experience exceptional funding is, in practice, simply not available. The Coalition Government has indicated it's plans to abolish legal aid for preliminary (pre-hearing) advice.