Francis Middleton Milne, known as Frank, was born on 11 December 1891 at Taieri Beach, Otago, to Scottish parents Rebecca McDonald and her husband, James Milne, a farmer. His rural upbringing taught him a variety of practical skills, but he did not settle to any occupation until, late in 1913, he became a porter and mountain guide at The Hermitage, Mt Cook. Presumably he was influenced by his elder brother, Charlie, who had been a guide for the previous two climbing seasons.
Frank Milne soon showed his ability as a climber and guide. His first recorded ascent was in January 1914 and within two months he was making significant climbs. He was taught by The Hermitage's chief guide, Peter Graham, and throughout his career he studied the theory and practice of his sport, developing marvellous balance, strength and judgement. The first of Milne's outstanding climbs was in February 1916, when he led client Sam Turner and second guide Jack Lippe on a grand traverse of Mt Cook. This was only the third time the feat had been accomplished, and it required step-cutting for many hours along the summit ridge.
Milne made the last climb of a fine season a few days later. He was not to climb again until June 1919 because of service during the First World War. He trained as a signaller and joined the 1st Battalion, Otago Infantry Regiment, in France in early 1917. After being wounded in May that year and badly gassed in September 1918, he was invalided home and discharged the following February. In spite of lingering health problems, Milne was determined to resume climbing. He regained his fitness, read widely about the mountains and became an expert photographer.
When Peter Graham moved to Franz Josef in 1922 Milne became chief guide at The Hermitage. Although he was a superb climber and taught younger guides well, he was unsuited to other aspects of the position. A quiet and reserved man, he did not enjoy being a host at The Hermitage and found it difficult to handle the varied demands of managing tourists and climbers. Furthermore, since Rodolph Wigley had leased The Hermitage from the government earlier in 1922 and opened it all year round, the chief guide's responsibilities had increased greatly.
Milne was at his best in the company of climbing companions of similar skill, when he could relax and show his sense of humour and excellence as a raconteur. On challenging climbs he sparkled with joy. He had an unerring ability to select the best route and he built up a great record of ascents, many of them fast and difficult by the standards of the day.
His notable climbs included taking the novice climber Wigley to the summit of Mt Cook on the first winter ascent in August 1923. A more enjoyable climb came in February 1925 when Milne and the English climber Ned Porter made a very fast ascent of Mt Sefton. The combination of a difficult mountain and splendid comradeship made it 'a perfect climb', according to Porter. Milne's last climb was his sixth ascent of Mt Cook, on 24 April 1925. A few days later, after a straightforward packing trip, he became ill and was hospitalised. He should have been at the height of his powers as a climber, but he would never return to the mountains.
Milne, who had never recovered fully from the gassing he received during the war, developed tuberculosis, which eventually led to his death at the age of 41 in Wakari Hospital, Dunedin, on 9 January 1933. Committed to his mountain life, he had never married. In spite of the interruption of war and the ill health that abbreviated his alpine career, Frank Milne was the outstanding climber and guide of his day.