Until the enactment of the Human Rights Act 1998, freedom of expression was a residual freedom that existed insofar as there were relatively few laws limiting it. In one particular case - and apparently only one - a right of free speech was guaranteed by statute.
Bill of Rights 1689
That the freedome of speech and debates or proceedings in Parlyment ought not to be impeached or questioned in any court or place out of Parlyment.
In other cases people were free to say whatever they wished subject to laws covering such matters as obscenity, blasphemy, sedition, incitement to racial hatred, defamation, official secrets, contempt of court, contractual restrictions in some areas of employment, and the developing law of confidence.
European Convention on Human Rights Art.10
(1) Everyone has the right to freedom of expression. This right shall include freedom to hold opinions and to receive and impart information and ideas without interference by public authority and regardless of frontiers. This Article shall not prevent States from requiring the licensing of broadcasting, television or cinema enterprises.
(2) The exercise of these freedoms, since it carries with it duties and responsibilities, may be subject to such formalities, conditions, restrictions or penalties as are prescribed by law and are necessary in a democratic society, in the interests of national security, territorial integrity or public safety, for the prevention of disorder or crime, for the protection of health or morals, for the protection of the reputation or rights of others, for preventing the disclosure of information received in confidence, or for maintaining the authority and impartiality of the judiciary.
Derbyshire CC v Times Newspapers  1 All ER 1011, HL
PP brought an action for libel in respect of articles in DD's newspapers alleging mismanagement of public funds. The House of Lords agreed with the Court of Appeal that the action should be struck out. It would be contrary to the public interest, said Lord Keith, for any of the organs of government to have the right to bring such an action. It is of the highest public importance that a governmental body should be open to uninhibited public criticism, and a right to sue for defamation would place an undesirable fetter on freedom of speech.
R v Home Secretary ex p Simms ) 3 All ER 400, Times 9/7/99, HL
Prisoners AA sought judicial review of the prison authorities' ruling that they could not receive visits from journalists unless the journalists undertook not to make use of any information obtained during those visits. The House of Lords, reversing the Court of Appeal, said a blanket ban on such visits was unlawful. A prisoner does not have an unfettered right to free expression, and cannot claim (for example) the right to take part in ordinary political debate through media interviews. But he does have the right to seek to persuade a journalist to investigate his claims to be the victim of a miscarriage of justice - it is not easy to conceive of a more important function which free speech might fulfil, said Lord Steyn - and this cannot be done effectively except through face-to-face interviews.