William Griffin was born in Britain probably in 1810 or 1811, the son of John Griffin and his wife, Ann Bolt. Very little is known of his life in Britain, but he is said to have been active in the Chartist movement. He arrived in Auckland, New Zealand, about 1842 and married a widow, Elizabeth Wallace, in St Patrick's Church, Auckland, on 10 June 1849. They had a daughter and a son. Griffin worked as a painter and glazier, but throughout his life was involved in promoting social reforms.
With the aid of the Auckland Building Operatives Society, which he helped to form in 1851, Griffin agitated for shorter working hours on Saturday afternoons, and established a working men's freehold land company, known as the Auckland Land Association. Also in 1851, with the backing of the society, he called a meeting to select a working men's candidate for the Auckland municipal elections. The response was unfavourable but, undaunted, in 1853 Griffin promoted a meeting of the 'operative and labouring classes' to select candidates from among themselves for the newly established Auckland Provincial Council. Three men were chosen, Griffin among them, but the committee later decided to have only one candidate, James Derrom, who gained election. Griffin stood at the next provincial council election in 1855 but was defeated.
Griffin next resumed his agitation for shorter working hours. In the other main centres the eight hour working day had become established, but not in Auckland. Late in May 1857 Griffin attended a meeting of the House Carpenters and Joiners Society, where he moved that a public meeting be called to discuss the reduction of daily working hours from ten to eight. That meeting, held on 8 June, decided to introduce the eight hour day within three months and to do so in agreement with the employers 'on the principle of Moral Suasion'. There was some opposition, but Griffin argued that workers were expected to help govern the country and that an eight hour day would give them leisure to educate themselves. A committee elected at the meeting promoted the campaign and on 1 September 1857 the new working hours, 8 a.m. to 5 p.m. with an hour off for lunch, came into force in Auckland.
This success helped Griffin to gain election to the provincial council in October 1857, on the 'Constitutional Party' ticket. He sat on the council for four years until September 1861. During the depression after the withdrawal of imperial troops Griffin promoted the Flax-Hackle Benevolent Association, which distributed hackles to the unemployed so that they could engage in flax dressing as a means of support. He agitated for the opening of the Thames goldfield in 1867, and at the request of a meeting of the unemployed, went to Thames to explore the prospects there. Lack of work in his own trade induced him to move to Thames where he worked as a miner and, according to an obituary notice, 'took a leading part in the various public agitations on the goldfield'. He also contracted a liver disease in Thames which hastened his death, in the Auckland Provincial Hospital, on 13 July 1870. The memory of Griffin's achievement was revived in 1890, when the Auckland Operative House Painters Union launched a fund to erect a memorial over his grave.