[4] Warner was one of the three surveyors (the other two being Robert Dixon and Granville Stapylton) sent by New South Wales Governor George Gipps to the Moreton Bay penal colony, arriving on the Sarah Jane.
[4] Circa 1847 Warner's next major role was to survey the Port Curtis area as part in the attempted settlement of North Australia,[4] a proposed new colony with its capital in Gladstone, which was initiated by the British Colonial Secretary William Ewart Gladstone but lasted two months as a change in the British Government saw Earl Grey become the British Colonial Secretary who cancelled the settlement.
Due to communication with New South Wales being by sailing ship (a voyage of some months), the delays involved resulted in the settlement being established after it had been cancelled in Britain and then had to be abandoned when news of the cancellation eventually arrived.
[4] Following his retirement in 1884 from the Survey Office, in September 1884 Warner was appointed Sergeant-at-Arms of the Queensland Legislative Assembly.
[4][7] Warner died at age 77 at his residence Runneymeade in Albion on 6 May 1891 following a five-week illness.