The truth is not a defense if the truth is damaging. I.e. yes you may tell everyone the truth about someone, but if that person suffers damage as a result of that, you are still liable for the damage.
The judge can decide that *if* there was a compelling reason for the truth to be stated (such as the public interest), you aren't liable for the damage. But it's not a solid 100% defense, no.
In 2013 the libel laws were reformed as described above with the Defamation Act of 2013 - before that, yes, things were awful.
"The Defamation Act 2013 has introduced new protections for publishers. In particular, the public interest defence at s.4 of the Act offers a defence in libel when the publisher believed that the matter was in the public interest. The legislation should give publishers new confidence and reduce the occurrence of self-censorship." - from http://www.libelreform.org/