Former News of the World (NotW) editor Andy Coulson was trying to identify who was leaking information at the newspaper and not requesting for Calum Best's phone to be hacked when he sent an email instructing to "do his phone", a court has heard.
Coulson was asking then news editor of the now-defunct tabloid Ian Edmondson to check the phone records of NotW reporter Rav Singh who was suspected of leaking information to the television celebrity, a jury at the Old Bailey was told.
The trial over alleged phone hacking at the Sunday red top was shown an email sent by NotW reporter Chris Tate to Edmondson on the morning of May 20 2006 about a story involving the son of George Best and Lorna Hogan, who claimed to be having his baby.
"Had a call from Lorna Hogan last night claiming Calum Best had texted her at approximately 10.20 saying 'how can you be so low selling picture of unborn child?"' he wrote.
"She says he must have been alerted from within News of the World and that she had a similar text before our other story on pregnancy.
"She believes he is being tipped off in advance and freaked out last night threatening to go to Max Clifford today and that she should have stayed with him instead or returning to us.
"Doubt he'd be best pleased by her. Flakey (sic) as you know."
The jury heard that hours after the email was sent, Coulson sent a message to Edmondson asking, "you think Calum a leak?"
Edmondson replied claiming Mr Best had been "bragging" about having "close mates inside News of the World", the court heard.
Coulson then sent an email which stated "do his phone", the jury was told.
During cross-examination of police witness Detective Sergeant John Massey, Timothy Langdale QC, counsel for Coulson, said: "Andy Coulson's case was that 'do his phone' was not a request or instruction to hack Calum Best's phone.
"It referred to checking on the billing of another News of the World phone due to a suspected leak."
The court heard that Mr Tate's email was not initially found by police and only came to light in October, five or six days before the trial opened.
The jury was told that on May 11 2006 Stuart Kuttner, then managing editor of the NotW, was copied into an email containing a list of 799 "unbilled calls from Rav Singh".
Records showed that private investigator Glenn Mulcaire hacked Mr Singh's phone on four occasions on March 21 2006, the court heard.
Former NotW and Sun editor 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.
Coulson is also facing two allegations that he conspired with former NotW royal editor Clive Goodman, 56, from Addlestone in Surrey, and other unknown people to commit misconduct in public office - between August 31 2002 and January 31 2003, and between January 31 and June 3 2005.
Jurors were told yesterday that Edmondson, who is charged with conspiring to hack phones between October 3 2000 and August 9 2006, is "currently unfit" and will take no further part in the trial.
He will be tried by a different jury at a later date, Mr Justice Saunders ruled.