According to family information Edward William Seager was born in London, England, on 8 May 1828; he was baptised on 1 June 1828 at St Clement Danes, Westminster. Edward was the youngest of eight children of Fanny Fowle and her husband, Samuel Hurst Seager. Samuel Seager was a porter at the Inner Temple law courts in London, and Edward attended the choir school of the Temple Church, before working for three years at the Inner Temple as a clerk. After his father's death he met in 1849 a school friend, James Edward FitzGerald, who encouraged him to emigrate to New Zealand. On the death of his mother in 1851 he was able to act on this suggestion, and in August 1851 embarked on the Cornwall. He arrived at Lyttelton on 10 December.
Soon after his arrival, on 20 December 1851, Seager was enrolled by FitzGerald, now sub-inspector of police, in the local armed police force. He also held the position of assistant immigration officer. He was soon promoted to corporal in charge at Lyttelton, and in November 1853 to sergeant. By this time Seager was effectively in control of the small provincial police establishment. However, his social background prevented recognition being given to his position; when a sub-inspector was appointed in September 1853 the job was given to Charles Christopher Bowen, of a landed family, university education, and no policing experience.
On 7 June 1854, at Christchurch, Edward Seager married Esther Coster, daughter of a farmer, whose family had also arrived in Canterbury in 1851. They were to have twelve children, two of whom died in infancy. In 1855 Edward Seager was again passed over for the position of sub-inspector, by a friend of FitzGerald's of higher social standing, John O'Neill. Seager, however, remained the working head of the force, and on 19 October 1858 was finally promoted to sub-inspector.
At Lyttelton Seager found ample opportunity to indulge a strong sense of humour and a love of practical jokes. One night the prisoners in the lock-up, a flimsy, A-frame construction, took up the floor boards, lifted the building and walked away with it. Seager arranged ropes and stakes in such a way that the escapees unknowingly headed towards the police station further down the hill. It was Seager who apprehended the accused sheepstealer James Mackenzie in March 1855; donning a disguise, Seager found the Highlander in the attic of a shanty.
In early 1862 a Victorian policeman, Robert Clarke Shearman, was appointed head of the Canterbury police. Edward Seager now became warden (later gaoler) at Lyttelton gaol, and Esther Seager became matron. By now the gaol had expanded considerably from its small, makeshift beginnings. In 1851 there had been 51 committals to the gaol; in 1862 there were 250. In April 1863 the gaol housed 100 inmates, including 17 'lunatics'. A smaller institution, also under Seager's control, was built at Christchurch that year.
From the late 1850s concern had been expressed, both to the Canterbury Provincial Council and publicly, at the unsuitability of housing mentally disturbed prisoners at the gaol. This situation was not peculiar to Canterbury. Only Wellington at this time had a separate institution for the mentally ill. Seager had an outhouse built beside the gaol for such patients, and, with others, campaigned for a proper institution. By 1862 the provincial council had been convinced of this need and in August 1863 the Canterbury Asylum, in Lincoln Road, Sunnyside, was completed. Its name was changed a year later to the Sunnyside Lunatic Asylum.
Edward Seager was appointed warden, or 'keeper', at Sunnyside, and Esther Seager, matron. They were to work there until 1887. With their four children, and 17 patients, the Seagers moved into the new building at the end of November 1863. They were supported initially by a staff of five attendants and a cook, and later also a chaplain and a resident doctor. By the mid 1880s the asylum housed over 300 patients.
Edward Seager saw the role of the asylum as one of rehabilitation, not incarceration. His treatments were based on the concepts of occupational therapy and therapeutic healing, methods he had already been using with the prisoners at Lyttelton gaol. Gardening, sewing, laundry, and eventually a number of craft workshops occupied the patients' time. Seager had a particular interest in theatre, and he put to use his talents as a magician, singer, pianist and organist in arranging plays, concerts, singing classes and other entertainments. Outdoor games and excursions were organised. An organ, built in England by his brother, Samuel Hurst Seager, was installed, paid for by public and private subscriptions. Books were supplied, and by May 1869 a printing press had been purchased by private donation, and the Sunnyside Press was launched.
Sunnyside became a community affair. The public were encouraged to visit and attend the entertainments. Travelling dramatic companies and local amateur groups gave performances. Until a nearby church was built, local people attended Sunday services in the asylum chapel.
Seager's methods were progressive for their time, and they were successful. A deep sense of humanity and personal concern for his patients marked his relationship with those he called his children. The benefits to the patients were attested to not only by visiting doctors, inspectors, and comments in the visitors' book, but by the testimony of the patients themselves. Wrote John Tyerman, on his discharge from Sunnyside in March 1870, 'He seems to treat all the patients…as a kind friend rather than as the official head of the establishment.'
Lacking formal qualifications, however, Seager fell victim to the expansion and institutional development of the country's asylums. In 1871 a parliamentary Joint Committee upon Lunatic Asylums had recommended that any such institution with more than 100 patients be headed by a qualified medical superintendent. Seager, however, was allowed to stay. With the abolition of provincial government in 1876, Sunnyside came under general government control, and in September 1880 Dr W. E. Hacon, formerly assistant physician to the Warwick County Asylum, England, was appointed medical superintendent. Seager took a year's leave to investigate asylums in England, and on his return in November 1881 was appointed steward at Sunnyside.
Inevitably, the appointment of a qualified, resident medical superintendent undermined Seager's position. In April 1887 both he and Esther Seager were asked to retire. After six months' leave of absence they were informed that, contrary to their expectations, no other positions had been found for them. They applied for, and were awarded, financial compensation.
After leaving Sunnyside the Seagers took in paying guests for a time. In 1889 Edward Seager was appointed usher to the Christchurch Supreme Court. He retired from this position in 1909. Until 1910 he was also librarian for the Canterbury Law Society.
Seager had pursued his cultural interests in the wider community. He was a founding member of the Lyttelton Choral Society and the Christchurch Musical Union. His theatrical talents were passed on to his family, who participated in the entertainments at Sunnyside, and notably to his grand-daughter, Ngaio Marsh. Although of a nonconformist background, he was also active in the Anglican church. Edward Seager died at Christchurch on 14 July 1922.