Alastair Campbell is joining the public relations giant Portland in his first in-house communications job since leaving Downing Street in 2003.
The former communications director to Tony Blair joins Portland as a strategic consultant and will work alongside its founder and his one-time No 10 deputy, Tim Allan.
Campbell announced the move on Wednesday in a blogpost on the Portland website.
"I have had plenty of offers since I left Downing Street to join PR consultancies or go in-house. It was not something I ever thought, to be honest, that I would do," he said.
"But Tim Allan is nothing if not persistent and over the last few months, I have found myself working with Portland more and more, advising clients and helping develop their bright young staff."
Campbell said he will be involved in advising Portland's big-name clients, which include Google, Coca-Cola and GlaxoSmithKline.
The former No 10 spin doctor, who last week gave evidence to the Leveson inquiry into press ethics, has acted as a freelance consultant since formally leaving Downing Street in September 2003.
He returned to politics briefly in the re-election campaigns of Blair in 2005 and Gordon Brown's unsuccessful run in 2010. Last year Campbell was reportedly involved in a media campaign to boost the overseas image of Kosovo.
Campbell worked as press secretary for Blair from 1994, joining Portland's Allan, who worked for the former Labour prime minister from 1992 to 1998.
He now joins former Downing Street officials Martin Sheehan and Mark Flanagan at the London PR agency, as well as the ex-Tory MP Michael Portillo.
Campbell added: "I'm not sure when I was in No 10 that I ever thought I would be working alongside Michael Portillo but then I think even Michael will admit he's changed his outlook more than I have."
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