The offence of seditious libel covers words or conduct intended to incite disaffection or contempt against the Queen, against either House of Parliament, or against the Courts, or to incite violence as a means of changing the law.
R v Aldred (1909) 22 Cox CC 1, Coleridge CJ
A journalist D wrote an article criticising the colonial government of India, and was charged with seditious libel. The judge said the test was whether the language used was calculated to provoke public disorder or physical violence in a matter of state: mere criticism, even in strong terms, was not enough. [The Old Bailey jury then convicted on the facts.]
R v Caunt (1947) 64 LQR 203, Birkett J
A man D published an anti-Jewish article in a North Lancashire paper, and violence subsequently occurred in Liverpool, some considerable distance away. Applying the dictum in Aldred, the judge directed the jury that an intention to stir up violence or general disorder was needed for sedition, and the jury acquitted on the facts.
R v Chief Metropolitan Magistrate ex p Choudhury  1 All ER 306, DC
A Muslim A sought judicial review of the magistrate's refusal to issue a summons for blasphemy and seditious libel against Salman Rushdie for the insults to Islam in his book The Satanic Verses. Refusing his application, Watkins LJ said the offence of seditious libel demands not only proof of an intention to promote ill-will between classes of Her Majesty's subjects, but also proof of an incitement to violence or resistance or defiance for the purpose of disturbing the constituted authority.
Arrowsmith v United Kingdom (1972) 3 EHRR 218, EComHR
A was a pacifist, arrested and prosecuted for incitement to disaffection after distributing leaflets to members of the armed forces advising them of various ways of leaving the service. The Commission said this was a reasonable limitation on her freedom of expression, and declared her complaint inadmissible.