There are more pupils of secondary-school age in special schools in England than those of primary-school age. In 2016, 60% of the 88,009 pupils aged between 5 and 16 in special schools in England were of secondary age. This disproportionality can be viewed as an indication that inclusion of children with special educational needs in mainstream secondary schools is not being achieved. This two-part multiple methods study involved a standard empirical enquiry, used survey methodology with rating scales and open-ended questions. The second part used futures studies methodologies and focus-group evaluation techniques to develop a vignette of a school that successfully includes those children who are placed in special schools, at the time of this study which was then subjected to critique and evaluation by a variety of expert and stakeholder groups in several focus-group settings. The suggestions arising from these discussions informed the reformulating and development of the vignette. Analysis reveals that while school structure and organisation account for some of the explanations of over-representation, so do within-child factors, issues around relationships, processes and curriculum as well as exosystemic/chronosystemic factors. A vignette of a future school is presented, one that which includes the children who are excluded from mainstream schools at the time of writing. This paper highlights the unexplored phenomenon of secondary over-representation in special schools in England and presents an in-depth analysis of the reasons that stakeholders give to explain this over-representation. Uniquely, this analysis is then translated into a design of a possible future inclusive school.