This defamation act makes a lot of sense. Freedom of speech is and should be limited, even in the USA. You can't just say anything you please and expect nothing to come of you. Write a letter with "Chocolate BOMB" to an airport and see what happens.
In the UK we also enjoy the fact the politicians can't just outright lie in their Manifesto about other candidates or the current government. If/when they do, action is taken to correct or (when maliciously undertaken) to disqualify that person from running for public office.
It's a bit more limited than that: during election campaigns (which last a few weeks in the UK) it's illegal for anyone to lie about other candidates' personal character with the intention of affecting the vote.
Everything else is fair game and "personal character" is narrowly construed — it's about "the man beneath the politician" as one court put it.
There's also no legal bar to lying about your intentions in your manifesto, despite a few attempts to persuade the courts to create one.
This from the High Court of England and Wales —
"Can a promise of this kind give rise to an enforceable legitimate expectation?
Even if we had accepted that the relevant ministerial statements had the effect of a promise to hold a referendum in respect of the Lisbon Treaty, such a promise would not in our view give rise to a legitimate expectation enforceable in public law, such that the courts could intervene to prevent the expectation being defeated by a change of mind concerning the holding of a referendum. The subject-matter, nature and context of a promise of this kind place it in the realm of politics, not of the courts, and the question whether the government should be held to such a promise is a political rather than a legal matter."
(Wheeler v PM, a case about whether the PM was legally obliged by a manifesto commitment to hold a referendum on an EU treaty http://www.bailii.org/cgi-bin/markup.cgi?doc=/ew/cases/EWHC/...)
The UK's lack of free speech is farcical... people doing jail time for offensive tweets, etc. And as for it protecting the truth, libel laws have been used to keep reporting the facts of corporate poluting, etc., out of the press.
This shows the limits on speech freedom in the USA http://en.wikipedia.org/wiki/United_States_free_speech_excep...
In the UK we also enjoy the fact the politicians can't just outright lie in their Manifesto about other candidates or the current government. If/when they do, action is taken to correct or (when maliciously undertaken) to disqualify that person from running for public office.