As to the general question, no, a statement being true does not immunise it from an accusation of it being used to stir up or incite hatred, or at the very least such a defence is not defined within the Public Order Act 1986. We do have the Human Rights Act which protects Freedom of Expression, but whether you could use it or other defences is pure speculation on my part: I would need to see some actual caselaw.
I've attempted my own searches but have only encountered the usual suspects: holocaust deniers and their ilk. Please let me know if you find such a case because I genuinely think that would be interesting to debate, but debating over pure speculation and innuendo is very boring.