Paul Brown has overseen the official 'news grid' since he was recruited to Downing Street by former comms chief Alastair Campbell in 1998.
PRWeek has learned that Brown is preparing to retire at the end of March and that Robin Gordon-Farleigh, who performs a similar role at the Department of Health, is being lined up to take over as his replacement.
As Number 10's head of news planning, Brown is the keeper of the grid - the diary that lists Government events. The senior civil servant also chairs a weekly Wednesday meeting with Whitehall comms directors in which Government announcements are scheduled. As well as helping to gain maximum publicity for positive stories, his role also entails ensuring that potentially damaging announcements emerge on busy days and so receive minimal publicity.
Downing Street sources suggested that Brown's imminent departure would send shockwaves through Whitehall. 'It's the end of another era,' said one well-placed source. Another source commented: 'Forget the Alternative Vote referendum - losing Paul is by far the biggest threat to the coalition's survival this year.'
Alastair Campbell told PRWeek: 'I asked Paul to set up and run the grid system which has since been copied by many other governments and organisations in politics, campaigns and business.'
He added: 'Paul helped bring both co-ordination and strategy to government. The systems that he put in place, coupled with his attention to detail and sound judgment, meant that the centre knew what was happening right across Government.'
Portland partner Steve Morris, a former Downing Street colleague, said: 'Paul has become the lynchpin of the Government's strategic comms. He probably has more influence on comms than any other civil servant. His departure will leave a huge gap.'