The publisher of The Sun, The Times and The Sunday Times appointed Harri in May 2012 when it was still known as News International. He had previously worked as an aide to London Mayor Boris Johnson.
Harri's appointment was seen as a move to restore the company’s reputation after the phone-hacking scandal and the Leveson Inquiry. He later admitted that the News International name had become a "handicap" for its papers, saying the brand "had become famous for all the wrong reasons" – hence the change from 'International' to 'UK' in mid-2013.
In September, Rebekah Brooks returned to the company as its chief executive having been cleared of phone hacking charges in July 2014. Brooks had previously resigned in 2011. Dominic Mohan, The Sun's editor between 2009 and 2013, left parent company News Corporation in September, taking up a job at PR firm Outside Organisation.
In an email to staff this morning announcing he would leave on 18 December, Harri said: "I explained my mission in an interview with an inferior publication when I joined back in May 2012. That job is now done and I am grateful to everyone who helped achieve it – not least my executive colleagues and wonderful team in corporate affairs."
The "interview with an inferior publication" was a reference to an interview with The Guardian.
Harri went public with the news of his departure at 10am on Tuesday, sending out a series of seven tweets.
1/7 Just told the wonderful staff @NewsUK that I'm leaving the company in the new year— Guto Harri (@Guto_Harri) November 10, 2015
4/7 Thanks to all @NewsUK who helped restore morale, rebuild political bridges and combat the appalling coverage of the company— Guto Harri (@Guto_Harri) November 10, 2015
5/7 Immensely proud of @the_newsacademy promoting a noble profession and helping next generation of journalists on the ladder— Guto Harri (@Guto_Harri) November 10, 2015