Here is the definition of extremism drawn up by Her Majesty's Government, with the aim of forcing schools to recognise and report extremist influences on children:
Here are a few quick comments on some words and phrases which I'd like to see nailed down a bit more firmly (on the assumption that we can't just ditch the whole thing, which would be my preferred option!):
British - who is "in" and who is "out" when we use this word? Given that the British isles are home to a multiplicity of cultures, both ancient and more recent arrivals, can any sensible definition be placed on this?
values - this is a slippery word. Does it just mean "things that I or we consider valuable/important", or does it imply some relation to a wider 'value system' and narrative?
including - in this context, that has to mean 'including, but not limited to', which raises huge issues about what else might count as a 'fundamental British value'.
rule of law - this could so easily be used to quash legitimate protest against specific laws that it's terrifying.
individual liberty - just ironic, considering how utterly contrary to individual liberty this whole process is.
respect and tolerance - these words both need serious definition. Will we still be able to criticise other worldviews? Are atheists to be required to 'respect' my worldview even though they are convinced it is delusional? Am I to be required to 'respect' theirs even though I think it is demonic? And as for tolerance - I can tolerate lots of things whilst believing them to be desperately wrong; but only if tolerance is understood to mean basically 'put up with'. I would like some assurance that I am not going to be required to celebrate what I am convinced are erroneous and deathly views.
All in all, this particular venture into establishing a category of thought crime strikes me as dangerous, poorly thought through, and socially destructive.