Hubert Thomas Armstrong (known as Tim) was born in Bulls, New Zealand, on 28 September 1875, the sixth of nine children. His parents, Mary Newcombe and her husband, Martin Armstrong, were recent immigrants from Dublin, Ireland. Mary was a nurse and washerwoman and Martin, a blacksmith by trade, initially worked as a labourer. Tim left school at the age of 11, and worked in the flax-milling industry around Bulls and in the bush. In 1895 he began work as a miner at Waihi. On 7 March 1900 at Paeroa he married Alice Fox.
From 1901 the Thames Miners' Union had been seeking wage increases and less rigorous working conditions, but the management consistently refused. After some activity in the Thames union, Armstrong became involved in the new Waihi Amalgamated Miners' and Workers' Union and helped conduct its case in the Court of Arbitration in 1907, when little was gained apart from a modest wage rise. As a result, the Waihi Union, and Tim Armstrong, became radicalised, and thoroughly receptive to the new syndicalist message of the New Zealand Federation of Miners, forerunner of the New Zealand Federation of Labour. From 1907 to 1909 he served on the Waihi Borough Council. In October 1908 Armstrong was elected vice president of the miners' federation, and held office for two years.
As a consequence of this activity he was dismissed from employment and forced to leave Waihi. The family moved to the West Coast, settling at the coalmining town of Runanga. After working again as a miner, Armstrong became secretary of the West Coast Workers' Union, and sat on the Runanga Borough Council from 1911 to 1913. He moved to Christchurch in 1916, found work on the Lyttelton wharves, and immediately involved himself in the Christchurch labour movement, one of the strongest in the country.
Labour leaders were particularly concerned about the rising cost of living, the inadequate provision made for soldiers and their dependents, and the excessive jingoism of the wartime coalition. All these issues were crystallised – and the worst fears of labour leaders realised – when the government imposed conscription at the end of 1916. Armstrong, believing New Zealand workers had no quarrel with German workers, was prosecuted for sedition and sentenced to a year's imprisonment in Lyttelton gaol after he told a street-corner meeting that conscription was more about controlling and intimidating a disaffected proletariat than about beating Germany, and would be unnecessary if soldiers were adequately paid.
In 1919 Armstrong was selected by the New Zealand Labour Party for Christchurch North. He unsuccessfully contested the seat which, as a prosperous electorate, was unlikely to elect a trade unionist and convicted seditionist. Earlier that year, however, he had been one of the successful Labour candidates for the Christchurch City Council, on which he sat until 1925 and from 1927 to 1929. As a city councillor he vigorously promoted municipal public works and housing. From 1919 until 1922 he was employed as secretary of the Christchurch Tramway Employees' Union.
In 1922 Tim Armstrong was elected to Parliament for Christchurch East, an inner-city working-class seat which he held until his death. In Parliament he soon proved an able and articulate representative of working-class interests. Quick and assertive in debate, and occasionally abrasive (one National politician thought Armstrong thumped the desk 20 times a minute when he was really worked up), he was well read and had an excellent command of statistics. Speaking constantly on the need to increase wages, he championed the cause of the poorly housed, and of the unemployed, who were numerous throughout the 1920s. He advocated the development of secondary industry, and he often deprecated the country's dependence on farm exports, on one occasion criticising ministers who were content that New Zealand should be 'a cowyard' and 'only capable of thinking in terms of beef and butterfat'.
When Labour won office in 1935 Armstrong was appointed minister of labour and minister of immigration. In this capacity he steered a number of far-reaching measures through the House of Representatives. Probably the most significant was the Industrial Conciliation and Arbitration Amendment Act 1936, which enacted a standard 40-hour week, established a statutory minimum wage, and provided for compulsory membership of trade unions, thereby extending protection to many isolated workers not previously covered. In 1937 he attended the International Labour Organisation conference in Geneva, impressing delegates with his command of labour issues.
The Agricultural Workers Act 1936 and its 1937 amendment improved conditions of service and accommodation for the country's farm labourers (except for those on Maori land development schemes). Previous regulations related only to the standard of accommodation; the new measures extended to wages and other conditions, and were strong proof of Armstrong's skill as a negotiator. In conference with workers' advocates and the New Zealand Farmers' Union (the president of which, William Polson, was perhaps Armstrong's closest friend on the National benches), Armstrong agreed that the acts would operate independently of the Arbitration Court and be enforced by inspectors.
As minister of labour Armstrong promoted the swift improvement in pay and conditions for the country's numerous relief workers. The Employment Promotion Fund was greatly expanded, to enable subsidised labour to do such work as developing marginal farmland and improving local amenities.
After the 1938 election Armstrong was shifted to housing. John A. Lee had already initiated state housing, and Armstrong had little scope for innovation. He was adept, however, at defending the principles and administration of state housing against attacks by the New Zealand National Party. In 1940 he also held the health portfolio; in 1941 this was exchanged for public works and as minister Armstrong oversaw extensive construction of defence establishments. He was also responsible for the final passage of the much-delayed Soil Conservation and Rivers Control Act 1941, which set up a national system of catchment boards and provided for measures such as afforestation to promote soil retention.
Armstrong's last years were clouded by the Second World War. He was most unhappy when the government introduced conscription in 1940, and is believed to have opposed the measure in cabinet. In public, however, he defended its necessity, as long as conscription was accompanied by stringent price and other economic controls, and was not used against militant workers. To some degree, at least, this position was consistent with his views in 1916, and also with his deep loathing of fascism, expressed in the House as early (and unfashionably) as 1935.
On 8 November 1942 Tim Armstrong died in Wellington from heart disease, accentuated by bronchial complaints deriving from his days in the mines. He was eulogised as one who had devoted his life to the cause of the working class, and as a parliamentarian of integrity, who enjoyed firm friendships on all sides. A devout Catholic, he was given a state funeral in Wellington, and a requiem mass in Christchurch presided over by his old parish priest from Waihi, Bishop Matthew Brodie. He was buried in Christchurch, and many thousands of people lined the streets for the funeral procession. Flowers and wreaths, filling four trucks, were sent from all over the country in tribute. Armstrong was survived by his wife, Alice, four sons and a daughter. One son, Arthur Ernest (Tommy), followed his father as a Christchurch city councillor and a member of Parliament.