She was a special adviser to Jack Cunningham when he was minister of agriculture and is the latest Labour insider to move into the public-relations and lobbying sector. Lord Bell's companies have always had close links to the Conservatives.
Ms McGlynn's hiring is seen as part of Lord Bell's policy of trying to build close links with the highest levels of the Government. In April the ex-Labour spin-doctor David Hill was hired as a director of Bell Pottinger Good Relations. Tim Fallon, a lobbyist who worked for Tony Blair during the election campaign, is also at Bell Pottinger.
Concern has been expressed at the number of Labour insiders who have moved into PR firms. The "cash for access" affair in the summer highlighted several such companies.
Ms McGlynn, 30, was one of the elite group of politically appointed advisers brought into Whitehall after the election. She was key to Mr Cunningham's shake-up of his ministry, which he believed was secretive and out-of-touch. She was on the minister's Independent Advisory Group with Lord Donoughue and Baroness Young, but left the ministry after Tony Blair's reshuffle in July. Her former boss was promoted to become Cabinet co-ordinator and has been nicknamed "The Enforcer".
Ms McGlynn had been adviser to Mr Cunningham from 1993. Previously she worked as a researcher for the late John Smith and in the European Parliament. She has a degree in government from Essex University.