The first such case that came to light involved Tom Newton Dunn, political editor of the Sun. The Metropolitan Police wanted the name of one of his contacts, and knew better than to ask. So they ordered Vodafone to hand over his phone records. Vodafone obliged: under the law, it has to.

This month, another newspaper found it had been targeted by the police: the Mail on Sunday had spent £150,000 in legal fees to protect its source in the Chris Huhne speeding points saga — which it succeeded in doing. Until Kent Police secretly ordered the phone records of a Mail on Sunday journalist and found the source that way.