Samuel Haywood Mirams was born on 28 August 1837 in Minster, on the Isle of Sheppey, Kent, England, the son of Elizabeth Cole and her husband, James Mirams, a clergyman. He was educated at private schools at Blackheath and Twickenham before taking up employment at an architect's office in London. When he was 19 the family emigrated to Australia, where his father became rector of the Congregational church in Collins Street, Melbourne. Mirams worked for several years for the firm of Purchas and Swyer, architects and engineers.
In 1862 he travelled on the Aldinga to Dunedin, New Zealand, to carry out work for Purchas and Swyer; he decided not to return to Australia. Mirams worked for two years as a draughtsman and assistant engineer for the Otago provincial government, and for a further two years as an architect and engineer in private practice. He was one of the signatories to the 1864 deed of purchase for the Moray Place site of Dunedin's first Congregational church. He married Matilda Philippa Eastgate in the church's manse on 21 February 1865.
Early in 1866 Mirams was appointed to the position of city surveyor. His duties were 'of an exceedingly onerous as well as of an exceedingly varied character.' In 1878 he formulated a drainage scheme which became the basis of Dunedin's sewerage system. From 1880 he was in charge of the water supply systems at Silverstream and Ross Creek; the low-level supply at Water of Leith was added in 1886. Mirams was also responsible for the inspection of trivial works and repairs.
As well as overseeing the grading and finishing of most of the city's streets, Mirams was responsible for establishing and maintaining cemeteries, recreational reserves and reserves for leasing, the supervision of buildings and the administration of the city by-laws, particularly in relation to property. He is perhaps best known for the developments associated with the town belt: the creation of Queen's Drive and Maori Road, Woodhaugh Garden and the Northern cemetery. His proposal that telegraph wires should be carried underground was never carried out.
Mirams was incidentally involved in a scandal in 1886 when two women were killed in an accident caused by the incorrect handling of gelignite during blasting at the Princes Street cutting. Although Mirams was formally responsible for the project, the work was being supervised by the completely unqualified William Barnes; he had been appointed by his father, John Barnes, the mayor of Dunedin, whose interference in operational matters was widely held to be the ultimate cause of the accident.
On his retirement for health reasons in 1901 Mirams was retained for two years on full pay while his sole responsibility was the secretaryship of the Dunedin Drainage and Sewerage Board. The council, the public and the press paid tribute to his long and conscientious service, one editorial remarking that he had witnessed, partly as a result of his own efforts, 'the transformation of Dunedin from the condition of a practically unformed town to that of a fairly well equipped city'. On his death at Dunedin on 10 October 1911, it was said that he had 'left in the city a very noble monument of the services he had rendered it.' He had been widely respected for his 'exceedingly suave and courteous manner' and 'unobtrusive disposition'.
Matilda and Samuel Mirams, living mainly in the north end of Dunedin, raised a family of seven boys and four girls, many of whose descendants have maintained close ties with the city he helped to build. Matilda Mirams died at Dunedin in 1928.