Henry Ely Shacklock was born on 21 June 1839 in Kirkby-in-Ashfield, Nottinghamshire, England, the son of John Shacklock, stocking maker, and his wife, Mary Ely, who worked as a seamer, sewing up stockings for local manufacturers. His father died on 27 October 1841; he had one brother, John, and a sister, Emma, who was born four months after her father's death. Henry attended the parish school at Kirkby. In the mid 1850s he began an apprenticeship in the ironmoulding trade, and worked as an ironmoulder in various foundries in Nottingham and Derby. But he became dissatisfied with the opportunities available to him in England and emigrated to New Zealand.
Henry Shacklock arrived in Port Chalmers on the Bombay on 9 September 1862, and obtained work cutting scrub on the Otago Peninsula. In the middle of the following year his fiancée, Elisabeth Bradley, the daughter of a Derby tailor, arrived at Dunedin with Henry's sister, Emma, and her fiancé, John T. Evans. Henry and Elisabeth were married at Port Chalmers on 20 July 1863, and Emma and John at Oamaru on 24 July. Shortly afterwards the two families moved to Oamaru where Evans later became a prominent flourmiller. Around 1866 Henry's mother, Mary Shacklock, also emigrated to Oamaru.
Henry Shacklock returned to Dunedin in 1866 and built a house on a section between Park Street (now Ardmore Drive) and Grosvenor Street near the Oval. After another period in Oamaru he settled permanently with his family in Grosvenor Street. In late 1871 or early 1872 he began in business as an ironfounder, using family money for most of his capital. The South End Foundry, situated in Crawford Street across the Oval from Grosvenor Street, proved a successful venture, and Shacklock gained a reputation for skilled work as an ironfounder.
However, it was as a manufacturer of coal ranges that Shacklock made his mark. In 1873, as a result of requests from clients and out of dissatisfaction with the imported stove in his own house, Shacklock designed and built a coal range. After various modifications it proved successful, and became the basis of Shacklock's business. Named the Orion (because of Shacklock's interest in astronomy), the range was of cast-iron construction, did not need to be fully built in, and was well adapted to New Zealand conditions. The Orion coal range soon captured a large part of the growing market in the colony. Production increased, and the foundry was expanded. By the late 1880s models of various sizes were being made, as well as specialist stoves, although the No 1 Orion was the main line. In 1894 the firm employed over 40 men and its coal ranges were being sold throughout New Zealand. When in 1900 the firm was formed into a private company, H. E. Shacklock Limited, it had a capital value of £25,000.
Thus Henry Shacklock the ironmoulder from the Midlands became a prosperous manufacturer in colonial New Zealand. He had a keen eye for what the market wanted, and the skill to provide it. His talent in designing attractive ranges from the unpromising medium of cast iron is evident, as is his ability to organise production in a very cost-effective manner. Shacklock was not an entrepreneurial businessman, however. He stuck to what he did best, and although his name appears as a founding member of the New Zealand Manufacturers' Association in 1884, he did not play a big part in sectional organisations. 'H. E.' (as he was known in the factory) continued many of the craft-based industrial traditions of his Midlands training. The foundry was the basis of the firm, and Shacklock remained at heart an ironmaster. He was regarded as a just and fair-minded employer, who rewarded quality work and had a paternal interest in his workers.
A deeply religious man, Shacklock was a staunch member of the Congregational church in Dunedin. He was a foundation member of his local Kensington school committee and a supporter of technical education. An attempt to enter local politics in 1896 was unsuccessful.
Elisabeth and Henry Shacklock had five sons; one died in infancy and the other four eventually worked in the family firm. Elisabeth Shacklock was a woman of strong character. In the late 1890s she nursed Henry during his bouts of ill health, and became an increasingly dominant figure in the family. Henry gradually withdrew from an active role in the firm. He became prone to periods of depression, and on 17 December 1902 he hanged himself at his residence. Elisabeth died in Dunedin on 18 April 1916.