Is there free speech in (formerly Great)Britain?

Hell no.
There are two main causes of concern for Emerald. Firstly, the work could be seen to incite racial hatred and stir up religious hatred under United Kingdom law. Clearly you have no intention of promoting racism but intent can be irrelevant. For example, one test is merely whether it is “likely” that racial hatred could be stirred up as a result of the work. This is a particular difficulty given modern means of digital media expression. The potential for circulation of the more controversial passages of the manuscript online, without the wider intellectual context of the work as a whole and to a very broad audience—in a manner beyond our control—represents a material legal risk for Emerald.

Secondly, there are many instances in the manuscript where the actions, conversations and behavior of identifiable individuals at specific named colleges are discussed in detail and at length in relation to controversial events. Given the sensitivity of the issues involved, there is both the potential for serious harm to Emerald’s reputation and the significant possibility of legal action. Substantial changes to the content and nature of the manuscript would need to be made, or Emerald would need to accept a high level of risk both reputational and legal. The practical costs and difficulty of managing any reputational or legal problems that did arise are of further concern to Emerald.
Short version: "The law can see anything as hate speech if someone complains.  And even if your information is perfectly correct and documented, it could cause problems.  So we won't publish your book."