The fault can be squarely placed upon the shoulders of the Warnock Report of 1978 as subsequently enacted with vigour by various governments which resulted in the decimation of education provision as we knew it.
Lady Warnock, as she now is, virtually recanted (in 2005) all she had recommended.
For those who don't remember just what damage this left wing idiot caused a summary can be found here:
http://www.douglassilassolicitors.co.uk/UsefulInformation/SEN-EducationInfo/warnock.htmlFurther blame must of course go to Lord Scarman for his "findings" in his report on the flawed investigation into the Stephen Lawrence murder.
Anyone looking for reasons need look no further than these two.