Former royal editor Clive Goodman told the phone hacking trial that ex-News of the World editor Andy Coulson saw a transcript of a hacked voicemail left by Prince Harry.
Goodman told the Old Bailey that he was first alerted to the prince's message by private detective Glenn Mulcaire in December 2005 and then listened to it himself and made a transcript, which he went on to show Coulson, redacting the names with X and Y.
In an email read out in court, he told Coulson: "As you know it's 100% fact."
Asked by his lawyer lawyer, David Spens QC, why he says that, Goodman told the court it was because he had seen the transcript.
Goodman, 56, of Surrey, admitted phone hacking and was sentenced with Mulcaire in 2007.
He denies conspiring to commit misconduct in a public office. All the defendants in the case deny the charges against them.
More top news
A touch brighter to the southeast but still a great deal of cloud cover across the UK with patchy rain in the west.
A teenager has been expelled from school after posting insults about his headteacher on Facebook.
A former Fox employee has died after apparently shooting himself outside the front doors of the News Corporation building.