He became an MP in 1979, and quickly ascended to the shadow cabinet, holding the posts of Shadow Environment Secretary and Shadow Minister for London at the time of the 1997 General Election. After the victory of Labour, he was appointed to the poisoned chalice of Secretary of State for Health.
He resigned his ministerial position to stand as the official Labour Party candidate in the first Greater London mayoral election in 2000, but lost to the former Labour MP Ken Livingstone. Since then he has remained on the backbenches.