Prince Harry was bombarded by messages from 'needy' Chelsy Davy
The jury at the phone hacking trial at the Old Bailey heard how the News of the World's former royal editor, Clive Goodman, sent an email in August 2005 to the then editor Andy Coulson saying she was "blitzing him with dozens of calls" and "driving him nuts".
Miss Davy was also branded as "incredibly needy" by the Royal Family, according to Mr Goodman.
In an email written by the journalist to his editor he explained: "He's not allowed to use his mobile at Sandhurst until he's off duty but she's blitzing him with dozens of calls and texts when he should be concentrating on his training."
Harry could only field the calls when he had finished his training duties at 10pm, the email said.
The email went on: "Family likes her well enough but they're worried that she's incredibly needy, just at the time when Harry needs to be concentrating on himself."
Earlier in the trial the jury heard allegations that the newspaper used phone hacking to get stories on the royals, including a claim that the Prince broke the rules at Sandhurst by asking an aide for help with an essay.
The prosecution alleged that a story titled "Harry's aide helps out on Sandhurst exams" came from a voicemail illegally accessed by private investigator Glenn Mulcaire.
The story came from a voicemail message left by Harry for his private secretary Jamie Lowther-Pinkerton, asking for information to help with an essay, the court was told.
Mr Goodman, 56, from Addlestone, Surrey, and Mr Coulson, 45, from Charing, Kent face two allegations that they conspired together and with other unknown people to commit misconduct in public office between August 31 2002 and January 31 2003, and between January 31 2005 and June 3 2005.
Mr Coulson is also accused of conspiring to hack phones between October 3 2000 and August 9 2006.
That charge is also faced by former News of the World and Sun editor Rebekah Brooks, 45, of Churchill, Oxfordshire, Ian Edmondson, 44, of Raynes Park, south west London and former managing editor Stuart Kuttner, 73, of Woodford Green, Essex.
Mrs Brooks also faces two counts of conspiring with others to commit misconduct in public office – one between January 1 2004 and January 31 2012, and the other between February 9 2006 and October 16 2008 – linked to alleged inappropriate payments to public officials.
She also faces two allegations of conspiracy to pervert the course of justice – one with her former personal assistant Cheryl Carter, 49, of Chelmsford, Essex, between July 6 and 9 2011, and a second with her husband, Charles Brooks, and former News International head of security Mark Hanna and others between July 15 and July 19 2011.
The trial continues