We've talked before about online infringement for linking, which can cause liability for both copyright infringement and defamation (see here).
On the defamation side the Ministry of Justice has published guidance on the application of the website operator defence under section 5 of the Defamation Act 2013:
The purpose of the Defamation Act 2013 is to rebalance the law on defamation to provide more effective protection for freedom of speech while at the same time ensuring that people who have been defamed are able to protect their reputation.
In accordance with this aim, Section 5 of the Act creates a new defence to an action for defamation brought against the operator of a website hosting user-generated content where the action is brought in respect of a statement posted on the website
Practical tips in the guidance include: (i) a suggestion that website operators set up and publicise a designated email address for notices of complaint under section 5; and (ii) a suggestion that complainants identify where a statement was posted using a URL.