Harrow west has returned the Labour Co-operative who joined what? 
Harrow West (UK Parliament constituency): Harrow West is a constituency created in 1945 represented in the House of Commons of the UK Parliament and which has returned the Labour Co-operative MP Gareth Thomas in the five General Elections from 1997 having previously returned Conservative MPs. Gareth Thomas (English politician):  Thomas held the position of Minister of State at the Department for International Development and, following the 2010 election, joined the shadow frontbench team.
shadow frontbench team