He was Gordon Brown’s official spokesman from June 2009 until May of this year, before joining UK Trade and Investment as strategic comms adviser after the general election.
Before moving to No. 10 he was group corporate affairs director at Vodafone.
Lewis commented: ‘I am delighted to be joining AFME at such a critical time for the financial sector. This is an exciting opportunity for me to lead the only organisation representing the full spectrum of European financial institutions and which speaks from a position of authority and tremendous knowledge of the markets and how they work.
'By applying my experience of communications, advocacy and public policy I can help drive the agenda of AFME in its important work with legislators, regulators and other stakeholder groups.’
Mark Austen, AFME’s head of markets policy, who has been serving as acting chief executive, has been appointed chief operating officer.
Lewis came to national prominence when he began working for the Queen in 1998, helping stabilise Buckingham Palace’s reputation after the death of Diana, Princess of Wales.
He has also held senior comms posts at Centrica, NatWest Group and S.G. Warburg Group.