Right or wrongs notwithstanding, I am wondering how you can force someone (who has probably very little to lose right now) to give evidence without resorting to violence or threats thereof - in which case all bets are off as to the veracity of any statements made.

http://www.bbc.co.uk/news/uk-england-london-11687410

Yes that question did cross my mind as well. Cattle prod to the genitals was my immediate thought.

They would need some leverage on him, and possibly some form of deal would be brokered. Anything like this would have to be known so that the evidence can be viewed in the context of how it was given.

I think the Beeb's over selling it tbh, as they're keen to do these days

He could be given extra time for contempt of court for failing to speak. Though is a coroners inquest allowed to compel someone? Plus I would imagine that he would say nothing because he would incriminate himself and open the prospect to a retrial. Plus if he admits to any involvement he will get attacked in gaol. Child killers get a tough time in gaol.

I know what I would say in his place. I've always wanted to say it to a judge.

+1
We don't have "subpina laws (spelling?) like America.

subpoena

We do have something similar but I cannot remember what it is called. Though you cannot be compelled to incriminate yourself.