Paul William Barry Marsden (born 18 March 1968) is a British writer, businessman and former politician. He was the Member of Parliament (MP) for Shrewsbury and Atcham from 1997 until 2005. He was most prominently known for his anti-war views and crossing the floor twice (the first to do so since Winston Churchill), from Labour to the Liberal Democrats in 2001 and returning to Labour in 2005. Marsden is currently an International Business Consultant working on projects in Brussels and Amsterdam.