[3][4] He became a journalist in Auckland and edited the New Zealander then established the Anglo-Maori Warder, which followed an editorial policy in opposition to Governor George Grey.

[2] He was a member of New Zealand's first, second, third, and fourth Parliaments, representing the Bay of Islands electorate from 1853 to 1870,[3] when he was defeated.

[6][7] Carleton was the second Chairman of Committees, succeeding Frederick Merriman on 17 April 1856,[8] i.e. just after the opening of the first session of the 2nd Parliament.

[8] He had a strong interest in parliamentary procedure, and unsuccessfully lobbied for the position of Speaker.

He was also a critic of the idea that all voting districts should contain the same number of voters, saying that this system gave "a preponderating control" of the political world to one specific class.