[1][2] He was also the inaugural president of the Ceylon Branch of the British Medical Association[3] and a member of the Legislative Council for nine years.
[6] In the 1850s he worked as a physician at the Military Hospital in Colombo (his patients included the Governor Sir William Henry Gregory).
[6] He returned to Ceylon in 1858, where in August he was appointed to as the Colonial Surgeon of the Southern Province, a post he remained at until 1880.
[6][13][14][18] In November 1889 Dr Anthonisz led the local opposition against the Government's proposal to demolish the ramparts of the 17th-century Dutch fort.
Anthonisz argued that the fort provided protection from monsoon tidal floods and ships at anchor in the harbour[19] – a fact later proven with the 2004 tsunami.