[2][3] Mayo was educated at Downing College, Cambridge – reading philosophy – and City University Business School.

He led NEF from two to fifty staff, creating the leading 'think-and-do tank', looking at ethical market activity, local economies and public service reform.

NHS Foundation Trusts were an idea partly inspired by NEF and Mayo, particularly his October 2001 pamphlet, The Mutual State, published with Mutuo, a think tank set up by the Co-operative Party.

In July 2009, he announced that he would be resigning to take up the position of Secretary General of Co-operatives UK following the retirement of its chief executive, Dame Pauline Green.

He has advised HM Treasury on enterprise and led the development of the new Community Investment Tax Credit introduced by Gordon Brown.