Disgraced No 10 spin doctor Andy Coulson spent his first night behind bars after being jailed for 18 months for the phone hacking plot at the News of the World.
The 46-year-old father of three was given the " major share of the blame" after he was found guilty last week of conspiring to intercept voicemails at the now-defunct Sunday tabloid following an eight-month trial at the Old Bailey.
He spent the first night of his jail sentence at the top security prison HMP Belmarsh before he is transferred to a prison near his home in Kent.
The judge Mr Justice Saunders singled out the former editor for the heaviest punishment, describing the hacking of murdered schoolgirl Milly Dowler's phone as "unforgiveable".
He said: "Mr Coulson, on the jury's verdict, has to take the major share of the blame for the phone hacking at the News of the World."
"On the jury's verdict he knew about it and encouraged it when he should have stopped it."
On the Milly voicemail interception in 2002 which suggested she may be alive in Telford, he said: "The NotW delayed telling the police the contents of the voicemail until they realised that they were not going to find Milly.
"That was unforgiveable and could only, in my judgment, have happened with the knowledge of the person editing the paper that week, Andy Coulson."
He said their "true motivation" in hacking Milly's phone was to sell the most newspapers and not the best interests of the child.
The judge went on to say ignorance of the law was no excuse for what Coulson had done.
Following the sentencing, Coulson's former boss David Cameron said the sentence showed no one was "above the law".
On a visit to Scotland the Prime Minister, who last week apologised for hiring him in 2007, said: "Well, what it says is that it is right that justice should be done and no one is above the law, which is what I have always said."
There was no reaction from Coulson who arrived at court without his wife Eloise. He stood in the dock flanked by three former colleagues and private detective Glenn Mulcaire, who all admitted their part in hacking before the trial started last year.
NotW news editor Greg Miskiw, 64, from Leeds and chief reporter Neville Thurlbeck, 52, of Esher, Surrey were each jailed for six months.
News editor James Weatherup, 58, of Brentwood in Essex, was jailed for four months, suspended for 12 months, and ordered to do 200 hours unpaid community work.
The judge described Mulcaire, 43, of Sutton, south London, as "the lucky one", saying it would be wrong to jail him again after he already served a sentence in 2006 when he was first convicted of phone hacking.
The judge sentenced him to six months imprisonment, suspended for 12 months, plus 200 hours unpaid community work.
Mr Justice Saunders went on: "All the defendants that I have to sentence, save for Mr Mulcaire, are distinguished journalists who had no need to behave as they did to be successful.
"They all achieved a great deal without resorting to the unlawful invasion of other people's privacy. Those achievements will now count for nothing.
"I accept that their reputations and their careers are irreparably damaged."
He criticised the former newsdesk staff for not exposing what went on.
"There is a certain irony in seeing men who pride themselves on being distinguished investigative journalists, who have shed light in dark corners and forced others to reveal the truth, being unprepared to do the same for their own profession.
"I accept that that would require great courage but the best investigative journalists have never been short of courage."
Weatherup and Mulcaire both declined to comment as they left the courtroom.
According to Mulcaire's notes, Miskiw tasked him 1,500 times, Thurlbeck 261 times and Weatherup 157 times, the court heard.
Mulcaire, who was paid around half a million pounds by the NotW, was first convicted of phone hacking with royal reporter Clive Goodman who was told during the trial he would not face any more hacking charges.
Following the renewed police investigation into the full extent of hacking, Mulcaire admitted three more counts of conspiring to hack phones plus a fourth count of hacking the voicemail of murdered schoolgirl Milly Dowler in 2002 - an act which eventually led to the closure of the NotW in 2011.
While Coulson was in charge, the NotW was hacking a host of royals, celebrities, politicians and ordinary members of the public on an industrial scale amid intense competition for exclusive stories, the trial heard.
Prosecutor Andrew Edis QC said the Sunday tabloid was "utterly corrupt" and "became a thoroughly criminal enterprise".
The list of victims whose private lives were invaded read like a "Who's Who of Britain in the first five years of the century", he said.
Coulson's co-defendants Rebekah Brooks and managing editor Stuart Kuttner denied any wrongdoing and were cleared of all charges last week.