After standing unsuccessfully for Hackney Central in 1979, Bennett was elected to Parliament as the MP for Pembrokeshire at the 1987 general election. He served as member of the Select Committee on Welsh Affairs from 1987 to 1990, and the Select Committee on Procedure from 1988 to 1990, and was Vice-Chairman (Wales) of the Conservative Backbench Party Organisation Committee in 1990. He was appointed the Parliamentary Private Secretary to the Minister of State at the Department of Transport, Roger Freeman, in 1990, before becoming a Parliamentary Under-Secretary of State at the Welsh Office from 1990 to 1992.