Helen Connon was born in Melbourne, Australia, probably in 1859 or 1860. She was the second child of George Connon, a carpenter from Wales, and his wife, Helen Hart, who came from Scotland. Around 1862 the family moved to Dunedin, New Zealand.
'Never grudge any trouble that is taken for that child's education; she will repay everything that is done for her', was the farewell advice of Helen's Australian teacher. Helen's mother never did. In Dunedin she obtained for her intellectually gifted daughter the services of the young teacher and future politician Robert Stout. Three years later the family moved on to Hokitika, where the only education available for girls was at a dame school. Helen's mother now prevailed upon James Scott, the headmaster of a boys' school. At first reluctant to accept a girl, Scott (like all Helen's teachers) found her a rewarding pupil. She 'had qualities which made it a delight and a lasting possession to know her', he later wrote. Helen soon outdistanced her schoolfellows and at 15 began to help with the teaching. Convinced by Helen's success that girls were worth instruction, Scott opened a class for Hokitika girls and put her in charge.
Helen Connon was, in fact, destined to play a pioneering role in the education of New Zealand women. The momentous turning-point in her life occurred in 1874 after the family's move to Christchurch. That same year, John Macmillan Brown arrived in Christchurch to become one of the founding professors of Canterbury College. Helen's mother lost no time in pleading with him to admit her daughter as a student. A strong-willed and powerful man, Macmillan Brown agreed to enrol Helen as the college's first woman student. His decision settled once and for all the question of the admission of women to New Zealand universities. Matriculating in 1876, Helen Connon graduated BA in 1880 – the second woman arts graduate in the British Empire. When she gained her MA with first-class honours in English and Latin in 1881, she became the first woman in the British Empire to win a degree with honours.
Professor Macmillan Brown built up Canterbury College with extraordinary energy. Labouring from morning till midnight he expected similar efforts from his students. Helen Connon, who was a tireless worker, did not disappoint him. It is a measure of her dedication that in 1878, while still a student, she became one of five teachers at the newly established Christchurch Girls' High School. When she was appointed the school's second lady principal in 1882, she accepted as her life's work the task of making accessible to girls the educational opportunities which had, with some difficulty, been won for her. As well as English, her favourite subject, she taught Latin and mathematics. A sensible, far-sighted principal, she made Latin optional, introduced such practical courses as cookery, shorthand, bookkeeping, nursing and dressmaking, and expanded the teaching of science and physical education. Believing that physical and mental training should go on side by side (she herself enjoyed walking, rowing and horse-riding), she saw to it that tuition in gymnastics, swimming and tennis was available at the school. The exhaustion of pupils through overwork had no place in her educational philosophy.
Considered beautiful by her contemporaries, with brown hair and a strong, calm face, Helen Connon was widely admired, if not idolised, for her quiet dignity and kindness as well as for her intellect. While she was still a student John Macmillan Brown asked her to marry him. She made him wait seven years, until she had educated her two younger sisters and established Christchurch Girls' High School as the foremost girls' school in the country. They married at Christchurch on 9 December 1886.
Immensely proud at having succeeded against strong competition from other suitors, John Macmillan Brown settled with his wife at Holmbank, a stream-bounded property of five acres in Wairarapa Terrace. Here, with the help of a gardener, they planted trees, grew their own fruit and vegetables, and kept dairy cows, pigs, hens and horses. Helen Macmillan Brown loved animals and her practical skills ranged from skimming cream in the dairy to tending the horses. Their first child, Millicent Amiel (who became the mother of the poet James K. Baxter) was born in January 1888, and, after a miscarriage in 1895, a second daughter, Viola Helen, was born in November 1897.
Although the celebrated academic couple shared a great deal, marriage added to Helen's burdens. John was both immensely energetic and egocentric, at once giving and demanding much. In addition to his long hours of work, he made a practice of entertaining students and friends on Sundays from breakfast onwards – with his wife as 'helpmate'. She, determined to prove that it was possible for a woman to combine a demanding career with family life, remained principal at Christchurch Girls' High School for 12 years. But the strain took its toll on her health and she resigned in 1894.
In 1892 the couple spent some months in Britain and Europe, as they did again in 1896 accompanied by Millicent. On their third trip to Europe in 1900 they took the two children and a governess. But ill health struck. Although Viola recovered from a bout of pleurisy, Helen suffered a miscarriage and never properly recovered from the ill effects. In spite of this, she joined her husband on a prolonged and exhausting round of European sightseeing.
After their return to New Zealand nothing could alleviate the chronic insomnia which now plagued her. In January 1903, concealing from her vigorous husband a serious decline in her health, Helen travelled with John to Auckland. When she fell ill in Rotorua, the debatable diagnosis of diphtheria was made and the antitoxin unsuccessfully administered. She died on 22 February 1903, survived by her husband and two daughters, and was buried in Rotorua.