He was involved in the merger that created the state's first united conservative party, the Liberal Union in 1910, and served as its leader in the Legislative Council from 1913.

In this role, he was tasked with representing South Australia in England through the aftermath of the war; while there, he was knighted in 1921,[7] and was a commissioner of the British Empire Exhibition in 1924.

[1][4] Before arriving in London Lucas met Indigenous Australian Harry Hewitt in Victor Harbor, where he was taught by the latter how to throw a boomerang.

[8] Lucas used this knowledge to provide demonstrations of throwing the boomerang in London's Regent's Park, crediting Hewitt for his proficiency.

He made a final bid for political office at the 1928 federal election, unsuccessfully contesting a Senate seat for the Nationalist Party.