William Cavendish, 7th Duke of Devonshire, was born on 27 April 1808, the eldest of the four children of William Cavendish and his wife, the Hon. Louisa O'Callaghan, eldest daughter of Cornelius O'Callaghan, first Baron Lismore. His grandfather was George Augustus Henry Cavendish, 1st Earl of Burlington; William Cavendish, 4th Duke of Devonshire, was his great-grandfather. William Cavendish was styled as Lord Cavendish between 1831 and 1834; as Earl of Burlington between 1834 and 1858; and as the 7th Duke of Devonshire between 1858 and 1891. The changes in his title are reflected in the descriptions of documents, for example he will be referred to as the Earl of Burlington in diaries dated between 1838 and 1858 but as the 7th Duke of Devonshire in diaries dating from 1858 onwards.
Cavendish's father was killed in a carriage accident in 1812. He was educated at Eton College and Trinity College, Cambridge, and took his BA and MA in 1829, when he was second wrangler and first Smith's prizeman. In June 1829 he was returned as MP for Cambridge University, and two months later he married his relative, Lady Blanche Georgiana (1812–1840), fourth daughter of George Howard, 6th Earl of Carlisle, and favourite niece of William George Spencer Cavendish, 6th Duke of Devonshire. Blanche, almost a child bride, was as serious, earnest, and devout as her husband. They had three sons and one daughter: Lady Louisa Caroline Cavendish (later Egerton, 1835-1907); Spencer Compton Cavendish (1833-1908, later 8th Duke of Devonshire), Lord Frederick Charles Cavendish (1836-1882), and Lord Edward Cavendish (1838-1891).
When her uncle (the 'bachelor duke') took to religion in the 1830s, Blanche was a source of support and encouragement to him in his new-found sense of sin. When she died in 1840 (her doctors said of 'great nervous debility', but more probably of tuberculosis since she had been coughing blood) her uncle was almost as desolated as her husband.
Cavendish had no great political ambitions. He was ejected by Cambridge University in 1831 because he had taken the family Whig line in supporting the Reform Bill; he was immediately found another seat in the Fitzwilliam borough of Malton, and he was then translated to the Cavendish family Derbyshire seat when the incumbent, his grandfather, was created Earl of Burlington later that year. He was rarely heard from again in Parliament after succeeding to the Burlington title and estates in 1834. Those estates, in north Lancashire and Sussex, had come to the 4th Duke of Devonshire by marriage (along with vast Irish estates in Cork and Waterford), and had been left by him to his third, but second surviving, son.
He and his wife were greatly attached to the houses on the Burlington properties – Holker Hall in north Lancashire, and Compton Place in Eastbourne. The death of his wife at first turned Cavendish into a recluse at Holker, looking after its famous herd of shorthorns and resisting the 6th Duke's suggestion that he should move to Chatsworth with his four young children. Very soon he threw himself into the personal management of his estates which was to occupy the rest of his life. Furness was the first to absorb his attention, when he and the other great landowner in the neighbourhood, the duke of Buccleuch, played leading parts in launching the Furness Railway in 1843; this was designed to facilitate the transport of their slate and iron ore to the coast at the village of Barrow. Then from 1848 Cavendish became interested in the development of Eastbourne, and over the next forty years his investments in waterworks, gasworks, pier, and park, along with his patronage and the measures of his estate office to control the tone of development, were held to have been largely responsible for making Eastbourne into 'the Empress of watering places' (Eastbourne Chronicle, 4 June 1904). He also contributed to the development of Buxton as a watering place.
Furness was a different story. There nothing less was afoot than the creation, virtually from scratch, of a whole new industrial district, and the Duke found himself, sometimes reluctantly, drawn into the leadership of this process. The rise of Barrow as an industrial town, which began with the establishment of the Haematite Steel Company in 1859, was most directly associated with the enterprise and capital of the major industrialists, H.W. Schneider, Robert Hannay, and Sir James Ramsden. Behind them lay the capital and commitment to the economic expansion of the region manifested by the Duke. He never adopted a rentier attitude towards this part of his possessions; far from simply pocketing his mineral royalties and railway dividends he regarded it as a matter of self-interest and moral duty to use them to finance the further development of the region; and this continuing stream of investment, coupled with his close attention to all the businesses with which he became involved, made him into a regional entrepreneur of the first rank. The Park-Vale iron ore and Furness Railway ventures led on, with convincing economic logic, to his active involvement in the steel company and in the Barrow docks, once more in partnership with the duke of Buccleuch; and thence to the shipbuilding company which became the Naval Construction and Armaments Company (eventually sold to Vickers in 1896). He also invested in a shipping company and, using the growing pool of potential female labour created by the growth of Barrow and its male-dominated industries, in a flax and jute company.
Even before he succeeded to the dukedom Cavendish had committed more than £100,000 to Barrow enterprises. He then discovered that the 6th Duke had left the Devonshire estates saddled with debts of £1 million. He took measures to curb expenditure, and considered selling parts of the estates. He was persuaded that this would lead to loss of influence and social humiliation, and increased his exertions to nurture the great Barrow boom of the 1860s and early 1870s. Investment in the Barrow ventures increased steadily and for a while the dividends from them soared, so that at the peak in 1874 the Duke, with a gross income of more than £300,000, was probably the richest individual in the land, with more than half of his income coming from Barrow. Some of the inherited debt was cleared, but the Barrow investments necessitated some fresh borrowing, so that the overall debt remained much the same. Then, after 1874, misfortune struck. First, the whole British economy suffered a setback, and second, Barrow was hit especially hard by the ending of the 'Bessemer boom' in the steel industry (stimulated by Sir Henry Bessemer's process). The Duke's income from the Barrow enterprises collapsed from £150,000 a year in the early 1870s to barely £8000 a year at the end of the 1880s; in the same period he poured money into 'his' firms in a frantic effort to prop up the ailing steel, shipbuilding, shipping, and jute companies, so that at his death he left debts of some £2 million, all sunk in what had turned into unproductive investments. His eldest son, Spencer Compton Cavendish, 8th duke, was left to sort out this financial mess, and was astonishingly successful in the task.
The 7th Duke never appeared in society in London, reserving his public life for more serious pursuits, notably the support of higher education. He was the first Chancellor of the University of London, from 1836 to 1856, and an important influence on its early development. He was Chancellor of Cambridge University from 1862 until his death; he was Chairman of the Royal Commission on Scientific Instruction and the Advancement of Science, which sat from 1871 to 1874; and he provided for the Cavendish Laboratory at Cambridge in 1874. He was a considerable benefactor of Owens College, Manchester, and of the Yorkshire College of Science, Leeds; when these colleges became part of the new federal Victoria University in 1880 he was its first chancellor.
Cavendish supported Irish disestablishment in 1869 but opposed home rule and became a Liberal Unionist in 1886. Elected a Fellow of the Royal Society on 10 December 1829, he was made an honorary LLD of Cambridge, as well as being nominated a Knight of the Garter in 1858 and sworn of the privy council in 1876. He died at Holker Hall on 21 December 1891 and was buried at Edensor, close to Chatsworth, on 26 December. He was survived by his eldest son and his only daughter, Lady Louisa Caroline (d. 1907), who married Rear-Admiral Francis Egerton in 1865. His two younger sons, Lord Frederick Charles Cavendish and Lord Edward Cavendish, predeceased him. Lord Frederick was murdered hours after his arrival in Dublin as Chief Secretary for Ireland in May 1882, in the Phoenix Park killings.
Source: F.M.L. Thompson, 'Cavendish, William, seventh duke of Devonshire (1808-1891)', Oxford Dictionary of National Biography (Oxford: Oxford University Press, 2004). By permission of Oxford University Press.