He said there was a pressure to build up a list of contacts to provide a range of stories.
"You can get a front page on Sunday, but next Tuesday you have to have three fresh ideas and that's fine for a few months.
"But week after week after week there becomes a real pressure to build up a list of contacts from police officers to private investigators to basically anyone who can give you a story, and you lean on these figures to help you keep your job.
"I think Clive Goodman fell foul of phone hacking because he was getting on a bit.
"He was royal editor, he had a really high salary there and plenty of people who were 25-year-olds who would have taken his job and spent longer on doorsteps and worked harder, always snapping at his heels - in order to stay ahead of them he got himself into phone hacking."
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