Former News of the World news editor Greg Miskiw made some 1,500 taskings to phone-hacker Glenn Mulcaire, the Old Bailey heard today.
Miskiw – along with Andy Coulson, Neville Thurlbeck, James Weatherup and Mulcaire – are in court today for sentencing.
Prosecutor Andrew Edis QC told the court that Miskiw, 64, from Leeds, the most heavily implicated in phone-hacking of the journalists, made his orders between 1999 and 2006, some even after he had left the paper.
On 21 July, 2004, he asked Mulcaire to target Spectator publisher Kimberly Quinn over her involvement with former home secretary David Blunkett.
He and Thurlbeck were also responsible for instructing Mulcaire over the Milly Dowler hacking in 2002, the court heard.
In all, Thurlbeck's name appeared on 261 pages of Mulcaire's notes, Edis said.
Weatherup was the least involved in the plot, according to documentary evidence. His name appeared on just 157 pages of the private detective's notes.
Weatherup, Miskiw and Thurlbeck were all involved in targeting another former home secretary Charles Clarke over a false rumour he was having an affair – the court was told.
On the Blunkett hacking, Edis said: "It is absolutely clear from the evidence in the case that this whole series of events caused Mr Blunkett a great deal of distress and that he was the victim of a very deeply intrusive phone hacking."
In April 2006, Mulcaire was overloaded with hacking and mistakes began to be made, Edis said.
By then, the prosecutor said: "They are turning in on themselves. It is apparent from his notes Mr Coulson himself became a victim of his own conspiracy and others were also hacked."
Edis went on to apply for costs.
He said some of the defendants had given details of their financial status but Coulson had yet to give any information.
Edis said the maximum penalty for phone-hacking was two years in jail as set out by Parliament.
He added: "It may be thought that maximum penalty was not decided upon envisaging this kind of behaviour."