After attending Woodmill High School in Dunfermline, he studied Social Anthropology at the University of Sussex where he graduated Bachelor (Honours) in 1985. In 1990, he graduated Bachelor's Degree (Honours) with a degree in Divinity at the University of Edinburgh.
In May 2014 he became the Chief Executive Officer of the Edinburgh Cyrenians. He became assistant minister at South Leith Parish Church followed by a year as locum minister at Street Andrew"s Church in Gisborne, New Zealand. He then served from 1995 until 2002 as the minister of Street Margaret"s Parish Church in Restalrig, Edinburgh.
Aitken was elected as a Labour councillor to the Edinburgh City Council in 1999.
He served on the education and social justice committees. From 2002 he served full-time as a Councillor, including as the City Council"s Executive member for education.
From 2003 to 2006 he was COSLA"s education spokesman. In 2006 Aitken became Leader of the Edinburgh City Council.
Following the 2007 local elections, the Scottish Liberal Democrat and Scottish National Party groups agreed to form a coalition.
He did not seek re-election to the City Council at the local government elections in 2012. In 2011, Aitken contested the Scottish Parliamentary constituency of Edinburgh Eastern against the Scottish National Party"s Kenny MacAskill.
