There has been one development in the last few years - the "Reynolds" defence (after a case involving the ex Irish Prime Minister) of 'qualified privilege'. It's a bit hazy, but there are areas the court considers, if it accepts the libel was not done 'with malice':
The Telegraph, for instance, was told it couldn't claim this defence in the Galloway libel case, because it hadn't given him a chance to put their side of the story.
Now,
in my completely unqualified and untrained opinion, I don't think the BBC would be able to use this, because this isn't an urgent matter, and the information in question is generally acknowledged to be false, and the BBC know that; and it's not "in the public interest" that the question of who did what come out in this one-sided way - they could have a discussion programme on it quite easily talking about the commission findings, and interviewing the people concerned. They
might be able to say they've given Clinton et al a chance to comment if they get a short piece (interview, whatever) at the beginning or end of transmission to put their side. But I don't know if the BBC would want to do that anyway. I can't think of any case that has involved 'docudrama' - the BBC may think it's OK if it empahasises that some scenes are not based in fact. But if I were them, I'd be thinking of editing out the dubious scenes that have been talked about, and hang the continuity.