In 1856, at the first election held under responsible self-government, Irving was elected as the Legislative Assembly member for Clarence and Darling. This massive electorate covered an area extending from Grafton to Warwick. Irving's interests were mainly in the southern area of the electorate and he opposed the separation of Queensland as a separate colony. Consequently, at the next election in 1858, he lost the support of electors in the northern area of the electorate and was defeated. Irving re-entered the Assembly as the member for Clarence after the Darling Downs were placed in the new colony of Queensland in 1859. He was a tireless local member, who gained government support for improved river navigation, connection to the telegraph service and a gold escort. During his prolonged trip to England his seat was declared vacant due to absence but, despite still being abroad, he won the subsequent by-election.
