One reason is that companies, in spite of urgings from various bodies set up to examine best corporate practice, rarely give them the raw material or opportunity to do so.

ECONOMIST: Keep on purring

That's the conundrum posed by this weekend's sting operation in which the News of the World, Britain's best-selling Sunday tabloid, set up a group of people who, it says, wanted to buy bomb-making material on behalf of a Saudi backer.

ECONOMIST: Red mercury