Stephen was born in 1966 in Enfield where he attended the local comprehensive school, Southgate. He went on to study Politics & Economics at Oxford University.
In 1990 Stephen became the president of the National Union of Students. On leaving the NUS, Stephen was elected as a Councillor in the London borough of Islington.
In 1997 he defeated the then Defence Secretary Michael Portillo to win the constituency of Enfield Southgate.
He subsequently served as the Labour MP for Enfield Southgate for 8 years and was a Government Minister for 4 years between 2001-2005. He served as Deputy Leader of the House of Commons (2001-2) and as an Education Minister (2002-5).
Since June 2015, Stephen has served as the Chair of the International Development Select Committee. The purpose of this committee is to scrutinise the work and spending of the Department for International Development.
Stephen divides his time between Westminster and his constituency and has a flat near West Derby Village. He also holds weekly surgeries across the constituency. Stephen is also a patron of the Merseyside Motor Neurone Disease Association and the Amputees and Carer Support in Liverpool (ACSIL).
Stephen is a member of the shop workers trade union Usdaw.
Between 2005-2010 he worked for the Foreign Policy Centre, the Holocaust Centre and the Aegis Trust.
In 2010 he was elected as Labour and Co-operative Member of Parliament for Liverpool, West Derby with a majority of 18,467.
During the 2010 - 2015 Parliament, Stephen served as Parliamentary Private Secretary to Harriet Harman MP and was then part of the Shadow Foreign Affairs team. In October 2011, Stephen was appointed Shadow Secretary of State for Education. He then served as Shadow Minister for Political and Constitutional Affairs
In 2015, Stephen was returned as the member of Parliament for Liverpool West Derby, increasing his majority to 27,367