Frank Furedi is a Professor of Sociology but this is a work of social criticsm rather than sociological analysis.
Furedi thinks that "tolerance" has been redefined in (fairly recent)social practice to mean uncritical acceptance of diversity rather than recognition of the right to speak freely about things that matter (and even things that don't).
The intolerant person is now the person who does not accept (let alone welcome) diversity, who criticises other people's beliefs and lifestyles. Such people must, at the very least, be stigmatised and ostracised; in some cases, they should be prosecuted and silenced. Tolerance of diversity should be upheld by means of intolerance towards critics.
As part of the shift, the old John Stuart Mill-inspired notions - that the state should only act to prevent physical or material harms to others and that the (psychological) harm of being offended does not count - have been reworked so that the harm of offence is elevated to the same rank as other harms.
Furedi regards this shift and reworking as inherently paternalistic: individuals and groups are seen as psychologically vulnerable and in need of protection from both the careless and the careful words of others. They are not thought to be strong enough to have the thought that sticks and stones may break my bones but words will never hurt me.
"Free Speech" once meant that you could not only criticise but do it with gusto: Marx once wrote that you treat the ridiculous seriously when you treat it as ridiculous - and proceeded to do so. Woe betide anyone nowadays who thinks that such freedom remains.
Furedi does not work up his examples very satisfactorily and this may be because he too is inhibited by his academic milieu from saying what he thinks. Universities are now places where the route to success is the path defined by whatever currently counts as inclusive, responsible and politically correct. No one is interested in unpleasant truths, especially if they are truths.
Furedi misses a major element of classical liberalism, that its theory of liberty was the twin of a theory of authority. John Stuart Mill probably wrote more about authority and spent more time thinking about it than he did about liberty. His theory of liberty emerges in the context of developing an account of the kinds of authority (centrally, political authority) to which we should freely and rationally consent. The starting point for this account is an understanding of how authority in science is established. (See my essay, "Liberty, Authority and the Negative Dialectics of J.S.Mill" on my www.selectedworks.co.uk website).
Taking a look at this 19th century preoccupation with scientific authority would allow Furedi to improve on his briefly-expressed scepticism about peer review (pp.188-90).
This is a readable polemic which will be disliked by the Sunday School tendency among ecologists, feminists, postmodernists and those ridiculous people who call themselves relativists but become very agitated if anyone disagrees.