 The work of the Plunket Society was credited with lowering infant mortality in New Zealand from 88 per thousand in 1907 to 32 per thousand over the next thirty years, though it has since been argued that this was due less to its specific methods than to its general raising of awareness of childcare.King was appointed to represent New Zealand in 1913 at the Child Welfare Conference in London and was invited to assist in the establishment of a child public health service in Britain.Following the First World War he was one of the British representatives at the Inter-allied Red Cross Conference and travelled through Europe for the War Victims Relief Committee.