Harold John Finlay was born in Comilla, India (now in Bangladesh), on 22 March 1901, the son of David Finlay and his wife, Emma Matilda Thomson, who were Baptist missionaries from New Zealand. He was left a paraplegic after contracting poliomyelitus at the age of four. After the family returned to Dunedin in 1906, he was educated at North-East Valley School and the Dunedin Normal School. He excelled academically and in 1916 was the top student in the national public service examination. His mother, although now widowed and with limited income, encouraged him to pursue his interest in chemistry, and in 1918 he entered the University of Otago with a Beverly Scholarship and a university bursary.
Finlay graduated BSc in 1921 as the first Edmond research fellow in chemistry, and came second in the senior scholarship for physics; he also gained a prize for poetry. A first-year course in geology with W. N. Benson introduced him to the riddles of the fossil record and was the seed of his interest in palaeontology. Because of his disability, Finlay did not advance in geology, but Benson encouraged his interest in palaeontology and helped with his first paper on fossil Mollusca, completed when he was 20. He graduated MSc (with first-class honours in chemistry) in 1922; his potential in palaeontology was recognised by the award of a three-year national research scholarship.
Geology, as a historical science, requires a chronology to arrange the relative order of events in earth history. In the 1920s this was still unavailable for the vast monotonous sequences of soft mudstone and sandstone that form much of lowland New Zealand and record its history over the last 100 million years. Effectively, the pages of earth history lay scattered and could not be integrated into a coherent book. Over the next 30 years much of Finlay's research on fossils was directed at this problem.
During the tenure of his scholarship Finlay developed the methodologies that would mark his entire career: an encyclopaedic knowledge of the literature and critical evaluation of contemporary research; the formulation of problem-solving strategies and the construction of comprehensive databases; and detailed observation, rigorous testing and concise reporting. At the outset he built a large collection of fossil and modern Mollusca as a database. Physical disability did not prevent his participation in field excursions. He was strong and agile with his upper body, and student friends carried him to the major collecting sites. From one Oamaru site he collected over 40,000 specimens. Although this early research did not resolve the time-scale problem, knowledge of molluscan systematics was considerably advanced and Finlay was recognised as a leading scholar. He received the New Zealand Institute's Hamilton Memorial Prize in 1926 and a DSc in 1927.
For much of the next 10 years, however, Finlay's career was blighted by unemployment and poverty. He worked as a research biologist for the Fisheries Branch of the Marine Department from 1927 to 1929, but did not secure further professional employment until 1933 when, through the influence of John Marwick of the New Zealand Geological Survey, he spent 14 months with an oil exploration firm in Gisborne. In 1936, with unemployment affecting his personal life, he implored Marwick to give him further assistance.
Although he continued his research on molluscan systematics during this long nadir, Finlay also laid the foundations of a new research career using protozoan microfossils (foraminifera), previously neglected in New Zealand. When he joined the exploration group in Gisborne he had little knowledge of these fossils, no reference material and scant literature. Despite these impediments, he quickly demonstrated the utility of foraminifera as chronological indicators. It was a remarkable achievement and eventually led to his appointment in 1937 as micropalaeontologist with the Geological Survey. It was also a significant year in Finlay's personal life, for on 1 September, in Dunedin, he married Jean Dorothy Waterson Gillies; they were to have two daughters.
Finlay's research skills flowered at the Geological Survey. Renewed interest in oil and coal resources refocused attention on the need for a refined time scale and stimulated detailed stratigraphic studies. By examining 6,000 foraminiferal assemblages from throughout New Zealand, he was able to resolve problems that had confronted him since his earliest research. Finlay's phenomenal mental recall and ability to identify consistent distribution patterns were vital in this work. The culmination came in 1947 when he published, with Marwick, a time scale for the last 85 million years. Although presented only in outline, it has survived extensive testing and remains the basis of research on New Zealand's younger rocks. Finlay was elected a fellow of the Royal Society of New Zealand in 1939 and received its Hector Memorial Medal and Prize in 1941.
The intensity and focus of Finlay's scientific work also characterised his cultural and recreational activities. Music was an abiding passion, particularly the operas of Bizet, Verdi and Wagner. He played the piano from childhood and later confided that, given better health, he would have wished to be a concert pianist. As a student he built an extensive collection of recordings, and composed music and lyrics for student revues. From 1927 to 1932 he tutored in musical appreciation at Knox College.
The advent of the National Orchestra in 1946 rekindled Finlay's interest in composition, and several of his works were performed by the orchestra and chamber ensembles. He was a vigorous advocate of the nascent orchestra, and contributed articles to the New Zealand Listener on music and one of his other loves, bridge. A founding member of the Otago Bridge Club, he was instrumental in introducing the contract game, tutored during the depression years, and gave radio talks on the subject; he later represented Wellington in provincial matches. Finlay was also a keen philatelist, and his affection for cats led to his involvement with the Wellington Society for the Prevention of Cruelty to Animals.
A dominant, confident man of great vitality, who pursued excellence in all he undertook, Harold Finlay confronted physical and economic adversity and triumphed over them. However, his vigorous, often combative advocacy of his views, whether in science or the broader world, sometimes led to acrimony and dissension. He was not modest and seldom to be dissuaded. Harold's brother Martyn Finlay also achieved distinction in public life, becoming minister of justice and attorney general in the third Labour government.
Although his public persona suggested a difficult personality, Harold Finlay was a loving husband to Dorothy, who was an inspiration for his poetry and a partner in his many achievements. He was equally devoted to their daughters, for whom he wrote stories and illustrated poems. His final years of scientific eminence, cultural fulfilment and family affection were a fitting compensation for earlier years of hardship. One of the most remarkable scientists of his period, Harold Finlay died, unexpectedly, at his home in Wellington on 7 April 1951, survived by his wife and children.