You've got that arse-backwards, I'm afraid.
Under English Law, one may say untrue things about someone and not be liable (sic) for libel (sic). This would be true if you said Ian Huntley (a convicted child killer) is into beastiality, for example. He has such a lousy reputation anyway, it's impossible to further tarnish it, however outrageous a lie about him one tells.
But truth is an absolute defense against the charge of libel and slander in England, as it is (I imagine) everywhere. It's what it means; to libel (sic) is to tell a damaging untruth.