Career

Cornwell also served in the elected ACT House of Assembly (a predecessor to the ACT Legislative Assembly), representing the electoral district of Fraser, from 1975 until 1986 for the Liberal Party. Cornwell was initially elected the second ACT Legislative Assembly in 1992, elected to represent Molonglo in the Assembly in 1995, 1998 and 2001 general elections. Cornwell did not contest the 2004 ACT general election.

During his term in the Assembly, Cornwell served as Speaker of the Australian Capital Territory Legislative Assembly.