In Parliament, Heppell was appointed as the Parliamentary Private Secretary (PPS) to the Leader of the House of Lords Ivor Richard in 1997 and became the PPS to the Deputy Prime Minister John Prescott in 1998. He became a member of the Tony Blair government following the 2001 general election when he was appointed as a Lord Commissioner to the Treasury and Government Whip and was promoted within the Whips Office becoming the Vice-Chamberlain of the Household following the 2005 general election. He held this office until June 2007. He was a member of the selection select committee from 2001.