Before he was even one year old, Truby King almost died. Evacuated during the Taranaki Wars of the 1860s he fell ill with seasickness and diarrhoea. The doctor decided not to 'bleed' him, which he would have done for most ailments, and instead fed him arsenic and mercury.

After eight doses of poison, little Truby's father told him to leave the boy alone to die in peace. Miraculously, he survived but his health was never good. He would suffer gastroenteritis, bronchio-pneumonia, and pleurisy, and lose the sight in one eye due to tuberculosis...

After following his father into banking, King switched to medicine and at the age of 28, graduated from Edinburgh University as Master of Surgery. He took out the coveted Ettles Scholarship as the most distinguished student. Curiously, the top three students that year all hailed from New Zealand.

But what most set King apart was his overwhelming single-mindedness for anything that took his fancy. Credit for this probably goes to Henry Richmond, whose classroom was Richmond Cottage, one of New Plymouth's oldest surviving buildings. Richmond preached focus until a subject was fully mastered, so even when very young, King showed remarkable 'stickability'.

Child welfare reformer Sir Frederick Truby King is credited with drastically reducing infant mortality in his native New Zealand. His research also led to a radical improvement in childhood nutrition and he was knighted in 1925 for his contribution to society.

But for all of his laudable achievements, Truby King is undoubtedly best known as an early champion of enforcement parenting - with its emphasis on discipline and detachment.

The key to the Truby King method was to feed babies by the clock every four hours and preferably never at night - stoically ignoring demands for sustenance in between.

He recommended placing babies in their own rooms immediately and leaving them in the garden for long periods to toughen them up. He also imposed a 10-minute daily cap on cuddles.

Parenting was about routine and discipline. The formative months were for eating, sleeping and growing - not bonding.

King returned to New Zealand via Australia in 1920 and his association with Seacliff was soon to come to an end. In 1921 he took up the newly created post of director of child welfare, but found it much more difficult to pursue his enthusiasms within the government bureaucracy than he had working outside it with the voluntary Plunket Society. He continued to alienate the medical profession by blaming infant deaths and morbidity on unnecessary instrumental deliveries, and impinged on the territory of the school medical service with his pronouncements on inadequate school hygiene. It was probably to everyone's relief when, increasingly dogmatic and autocratic, he was diverted by his appointment as acting inspector general of mental defectives in 1924.

In the same year Bella King's health began to deteriorate rapidly and she was less able to fulfil her role as Truby King's mainstay, for theirs was very much a joint cause. Since its inception, and with her husband's oversight, Bella King had written the popular column 'Our babies', which appeared in 50 newspapers throughout New Zealand by 1914. She acted as her husband's secretary, organising their travel, writing reports on his behalf and answering correspondence. Her quiet order and intelligence provided a foil to his impetuosity and absent-mindedness. She welcomed her husband's recognition when he was made a CMG in 1917 and she lived to see him knighted in 1925....

Truby King's legacy, widespread in New Zealand, Australia and Britain, was the doctrine of feeding by the clock. Removed from the enthusiastic personality of its founder, the Truby King system became formalised into a set of rigid rules propounded by Plunket nurses. Yet King himself was a man who thrived on disorder. He ate at irregular times, paid no attention to the state of his attire, left travel plans to the last minute, was careless with money (once being declared bankrupt), talked interminably on his latest enthusiasm to anyone who would listen, and was impatient with opposition. There were many who found this total engagement with his latest mission attractive, while others found him irritating and eccentric. He is recorded, after his move to Wellington, as saying that he missed the insane.

Truby King was a singular man with a diversity of compelling interests. That he could arouse international enthusiasm for his infant welfare campaign testifies to his charisma. His status as a national icon was fittingly endorsed in 1957 when he became the first New Zealander whose image was inscribed on a New Zealand postage stamp. Although unimpressed by honours, he might well have enjoyed this tribute on something useful and transitory, but, above all, about communication.

The 1907 founding of the Plunket Society with its slogan to "help the mothers and save the babies" both reflected and propagated eugenic fears about the "unfit". "The destiny of the race is in the hands of the mothers", wrote founder Truby King. He believed the body was a closed system with a limited amount of energy. The education of girls, in anything other than domestic skills, used up their energy and could make them unable to breed or breastfeed. From his observations of patients as Superintendent of Seacliff Asylum near Dunedin he believed mental degeneration was caused by poor mothering. If only women could be taught the "science" of mothering the racial decline of the Empire could be arrested. Instead they would breed fit soldiers for the Empire. The less than perfect health of many soldiers enlisting in the First World War increased the Society’s influence.

The Plunket Society popularised the prescriptive ideology of a regime designed to build "character". It involved four hourly breast feeding (but not at night), toilet training from two weeks of age, fresh air, rest and no "spoiling" as playing with or cuddling the child could weaken "his" character.

But the Plunket Society was just one of many reactions by New Zealand society to those whose difference threatened the majority. Fear of the unfit and wishes to contain the disabled and undesirable had already led to New Zealand’s first public "lunatic" asylum in Karori in 1854. A larger one on the hills above the town of Porirua opened in 1887 and by 1896 its site covered 100 acres. Typically for the time, the Porirua asylum mixed several categories of "other": those with mental health issues, intellectual impairment, alcoholics, elderly and homeless people. For decades, these ‘inmates’ provided large captive communities for doctors and specialists to practice theories and interventions.

Some groups, such as those with vision and hearing impairments, were seen as "habilitable", meaning they had potential as worker citizens if they could be taught to speak or otherwise function in the "fit" world. Hence the establishment of residential schools which separated those with potential from their suspect families.

But certain types of intellectual impairment continued to be linked with "immorality". Girls’ and boys’ homes and farm schools were founded mainly to keep the genders apart and prevent criminality, deviant behaviour and, above all, reproduction. The 1911 Mental Defectives Act carefully classified groups of "other" into a hierarchy of idiots, imbeciles and feeble-minded. Special schools and special classes were provided for those deemed educable. The school medical service was founded to identify ‘defective’ children so they could be sent to the appropriate institutions and the 1914 Education Act made it obligatory for parents, teachers and police to report ‘mentally defective’ children. A residential school for ‘feeble-minded’ girls, Salisbury, was opened in Richmond, near Nelson in 1916.