How widespread is phone hacking?

The voicemail hacking scandal supposedly started as one or two bad apples at one newspaper, the News of the World.

Now as the Leveson inquiry into media standards rolls on we have gone from the bad apple theory, to the collapse of the News of the World, to questions about other Murdoch newspapers - and beyond the Murdoch empire allegedly to other newspapers in other groups.

Newsnight's, external Richard Watson has been trying to figure out how far the contagion may have spread.