David Cameron is the first prime minister to rise from the staff ranks of his own party — he is a true son of the Tory secretariat. You can read a profile of his days as a special adviser in Whitehall here.
David Crouch, one of the stakhanovites on the FT’s UK newsdesk, has worked up a list of the other “back room boys” that have made it into this cabinet:
George Osborne – special adviser to Douglas Hogg at ministry of agriculture (during mad cow crisis)
Andrew Lansley – Director of the Conservative Research Department (a short overlap while Cameron was political director)
Vince Cable - Special adviser to John Smith at Trade an Industry (a department Cameron also covered in his first job at CCHQ)
Nick Clegg – Adviser to Sir Leon Brittan as EU trade commissioner (so more a Eurocrat than Whitehall spad)
David Laws - economic adviser to Malcolm Bruce and then director of policy and research (he gave up six-figure bonuses in the City for the allure of the Lib Dem back-room)
Danny Alexander – former Lib Dem press officer
David Willetts – Former adviser to Lawson and Thatcher
UPDATE: John Dunford makes the very good point that the next prime minister is also likely to be a special adviser. Five of the Labour leadership hopefuls can claim to be a former special adviser: Miliband, Miliband, Balls, Cruddas or Burnham. This is truly the age of the Spad.