Margaret Lorimer, daughter of Jessie McLennan and her husband, James Lorimer, a ploughman, was born on 9 June 1866 at Inverness, Scotland. In 1871 her family emigrated on the Glenmark and arrived in Lyttelton, New Zealand, on 1 November. In July 1874 her father bought a section of land in Woodend, North Canterbury, and enrolled Margaret at Woodend District School. She left in 1878 and enrolled at Christchurch Girls' High School in September 1880. Placed in the fourth form, she had difficulties in subjects such as French and Latin, in which she had no grounding. Despite her late start, she won a University of New Zealand Junior Scholarship in 1883 and was capped MA with second-class honours in languages and literature in 1888. While still studying she had begun part-time teaching at Christchurch Girls' in 1886, and from 1889 was on the full-time staff with responsibility for mathematics.
In January 1897 Margaret Lorimer became headmistress of the Mount Cook Girls' School in Wellington. The primary school was in poor shape and she made a rapid improvement in the standards of teaching and discipline, as reflected in the increasingly glowing reports of the inspectors. It was a time of change in the teaching profession. George Hogben had been appointed inspector general of schools in 1899 and was determined to reform the system. Margaret Lorimer was involved at intervals from 1901 to 1905 in the work of committees he set up on matters such as superannuation, changes in syllabus, and staff and salaries. She urged in particular that the gap between the salaries of men and women be lessened. In the inspection report of 1905 she and her staff were commended for the spirit in which they had adopted the recommendations of the new syllabus, and in the annual report she was praised for the 'high standard of efficiency' the school had reached under her management.
Margaret Lorimer transferred from one shabby two-storeyed wooden building to another when she took up her position as principal of Nelson College for Girls in January 1906. For 19 years she was to live a spartan life upstairs in two small rooms among her boarders, and was to spend much of her leisure time helping to cater for their needs. She was responsible for all departments of the school and for most of her time had no secretarial help. Despite this she found time to see every girl at least once a week, to check on her speech, deportment and manners as well as her examination papers and sewing. There was little that escaped her eagle eye. With excellent deportment herself, dressed 'so like a dainty Dresden china figure' and wearing the neatest of high-heeled shoes, she made the most of her 60 inches of height. She could strike fear into the heart of the largest schoolgirl and, on occasion, of even a parent, and was often referred to as the Mighty Atom.
Margaret Lorimer had to deal with the continuing influx of free-place pupils and changes of syllabus. The state finance which became available for new classrooms helped, but the governors still required her to practise the strictest economy in running the school. Nelson salaries were among the lowest in the country until 1920, when a national salary scale based on grading was established. Even so, she kept an excellent staff and devoted much care to recruitment and training. She was a skilful teacher and administrator and under her regime the school grew steadily in stature. By 1922, however, she was feeling the strain of her unremitting work and in 1923 was granted a year's leave. In 1925 she was asked to work for another year and in December 1926 she retired.
Very soon after her arrival in Nelson, Lorimer began the habit of recuperating in the mountains after a stressful school year using either the Grahams' hotel at Waiho or the Hermitage at Mt Cook as a base. She rapidly developed both a deep love of the mountains and, through making many ascents with the guides Peter and Alexander Graham, the skills of a successful climber. She ascended one of her first peaks, Mt Moltke, in the summer of 1912 and in spite of the difficulties of cumbersome clothing and heavy equipment went on to have four successful climbing seasons in her 50s. Light, fit and nimble, she climbed Mt Cook in 1918 when she was 52. She showed her independent spirit by making a number of unguided ascents in the company of Horace Holl. She said that she was never so happy nor rarely so well as when she was in the mountains. A member of the New Zealand Alpine Club from 1924 and of the Ladies' Alpine Club, London, she never lost her interest in climbing and climbers.
Margaret Lorimer began her retirement with a prolonged trip overseas. After her return in 1931 she lived at Sayes Court, a private hotel in Wellington. She kept herself very busy, in particular helping to found a Wellington branch of the Nelson College for Girls Old Girls' Association. She also became an active member of the League of Mothers, serving on the dominion executive from 1936 to 1947 and editing their magazine until she was 78. Lorimer never married and died in Wellington on 29 October 1954.