Ryan studied sociology and worked as a teacher, before becoming a Labour councillor on Barnet London Borough Council in 1990, serving as deputy leader of the council from 1994 to 1998. She was a government whip under Tony Blair from 2002 to 2006, a junior Home Office minister responsible for ID cards from 2006 to 2007, and the Prime Minister's Special Representative to Cyprus from 2007 to 2008, when she was sacked. She lost her seat in the 2010 general election after an expenses scandal and was deputy campaign director of NOtoAV in the 2011 Alternative Vote referendum.