The 45-year-old told the Old Bailey she only found out on July 4, 2011 that 13-year-old Milly’s messages had been illegally accessed by the newspaper, and had known nothing about the tasking of phone hacker Glenn Mulcaire at the time.
As she returned to the witness box for the third day, the former News International chief executive was questioned about the 2002 story of the missing Surrey schoolgirl, which was to go on to bring about the Sunday tabloid’s downfall.
Brooks, who denies conspiring to hack phones, conspiring to commit misconduct in public office and conspiring to cover up evidence to pervert the course of justice, revealed she did not know when she was editing the NotW that hacking was illegal.
She also told the court that hypothetically, if there was a strong enough public interest for a story, she might have authorised hacking while she was editor.
Asked about her reaction when she found out in 2011 that Milly’s phone had been hacked by the NotW when she was at the helm, Brooks, of Churchill, Oxfordshire, said: “Shock, horror, everything.
“I was told that the NotW had asked someone to access Milly Dowler’s phone while she was missing, that they had also deleted her voicemails and for a period of time because of that her parents had been given false hope and thought she was alive.
“I just think anyone would think that that was pretty abhorrent, so my reaction was that. That was what I was told.”
Milly disappeared on March 21, 2002, the court heard, and while still missing, her voicemails were hacked the following month, between April 10 and 12.
The court heard that Brooks was on holiday in Dubai with then-partner Ross Kemp from April 7- 14, leaving her then-deputy Andy Coulson, a co-defendant in the trial, in charge.
Under questioning from her lawyer Jonathan Laidlaw QC, Brooks said the fact that private investigator Glenn Mulcaire — who has pleaded guilty to phone hacking — had been tasked with hacking Milly’s phone was never brought to her attention before July 4, 2011.
She said she did not remember any discussion about Milly’s disappearance when she checked in with her staff, and did not recall leaving a conversation in Dubai to take a phone call about the missing schoolgirl.