Alexander, Sir Jerome (1590–1670), judge and administrator, was born at Gressenhall, Norfolk, the eldest son of Jerome Alexander of Thorpland in Norfolk. Schooled at Aylsham, he entered Furnival's Inn on 1 July 1609, and also matriculated at Caius College, Cambridge, on 11 September that year. He served as steward to the earl of Arundell, before being made clerk to the court of star chamber, and he was appointed bailiff of Eynsford, Kent, in 1620. In the meantime he had entered Lincoln's Inn on 15 February 1617 and was eventually called to the English bar (28 June 1623). He was fined, imprisoned, and disbarred by star chamber on 17 December 1626 for forging legal documents in one of his cases. Arundell managed to secure his release and Alexander travelled to Ireland in 1627 with a recommendation to the lord chancellor, Adam Loftus (qv); he was admitted to King's Inns and began to practise law, soon attracting a number of powerful clients, including Viscount Conway (qv), whom he served as legal adviser and as land agent for his property in Down and Armagh. On returning to London in summer 1633 he was imprisoned again, but on 7 December he was released and pardoned for his offence of seven years before on condition that he did not practise in England.
His future apparently secure, Alexander set about acquiring an estate in Ireland: he leased the manor of Kilmainham, Meath, from Lord Barnwall for forty-one years for £1,200 in 1634, and established his residence there; in 1635 he purchased Magennis lands in Down (which he sold at some point after 1639), and in 1636 paid £4,200 for the barony of Kilcooly, Co. Tipperary. In 1634–5 he sat as MP for Lifford. He fell foul of Lord Deputy Thomas Wentworth (qv) by initiating a scheme on behalf of his patron Arundell, whereby Arundell could possess a massive territory in Wexford, Tipperary, and Kildare; he also claimed that Wentworth had opportunistically grabbed land near Naas after Alexander had discovered that the occupiers had no title to it. Fearing vengeance he went to London in the autumn of 1637 without licence and was imprisoned on his arrival. In his absence Wentworth dispossessed him of Kilcooly.
After being released in March 1638 Alexander fled to the continent, but returned to London in 1640 to provide evidence for Wentworth's treason trial in spring 1641. He went back to Ireland but had been there for only five weeks when he was forced to flee by the outbreak of rebellion in October 1641. He spent the next six years in London, where he served parliament, sat on a number of committees, and acted as treasurer for the adventurers of Ireland, being himself also a subscriber. He came close to being dismissed as treasurer when it emerged that he was an associate of Arundell, who was a catholic. In 1643, and again in 1644 he was imprisoned on charges of misappropriating funds voted by parliament to be used against the Irish rebels. During the second period of imprisonment he wrote A breviate of the sentence against Mr. Jerome Alexander (1644), in which he outlined his chequered career to date. He was acquitted of the charges against him and was still working for the adventurers in London in May 1647, but in 1650 he appears in Brussels, providing financial aid for the exiled royalist court, and he was still in the city in March 1653.
By 1655 Alexander had returned to Ireland, where he resumed both his legal practice and the treasurership of the adventurers; he became a member of the commission to determine the boundaries of forfeited estates, a role that made him useful to the government. In that year he renewed his lease on Kilmainham for ninety-nine years and in 1657 he was granted land in the barony of Fertullagh in Westmeath. But he was in financial difficulties and in 1658 petitioned the government for relief. He sat in the 1660 Irish convention for Belfast, strongly supporting the movement towards a restoration of the monarchy. He was in London in 1660 for the arrival of Charles II, ready to call in past favours. His manoeuvres were successful as he was knighted on 18 June 1660 at Whitehall, was made second justice of common pleas in Ireland on 19 January 1661, and was restored to Kilcooly on 16 February following.
In 1661 Alexander challenged Sir William Aston, second justice of king's bench, to a duel over a matter of precedence, for which he was nearly dismissed. His harshness as a judge was proverbial and on one occasion he refused to allow a man sentenced to death for stealing a sheep to plead benefit of clergy. It was largely owing to his merciless disposition that the duke of Ormond (qv), the lord lieutenant, sent him on a special commission to try tories on the Ulster–Leinster border in 1666, though Ormond disliked him and had vetoed his appointment as chief justice of the common pleas in 1664. Although he must have taken the covenant as a supporter of parliament in the 1640s, he was also noted for his eagerness to prosecute nonconformists, and was sent on assize to Ulster where presbyterians were most numerous. In May 1665 he became one of the agents in Ireland of the duke of York, later James II (qv), who was to be given confiscated lands which had belonged to the regicides. Alexander and other agents acted in the most unscrupulous manner, seizing land to which the duke had no claim and leasing it for their own benefit. They also hindered the workings of the second court of claims. In May 1668 Alexander quarrelled furiously with the court's commissioners and was described by one of them as the chief knave.
Alexander died on 25 July 1670 and was buried at St Patrick's cathedral in Dublin. He had married, in 1623, Elizabeth, daughter of John Havers of Norfolk. She died in 1667, having borne him sixteen children, but he was survived by only three daughters. His will is a remarkable and lengthy document, with many interesting bequests. Most of his property was left to his youngest daughter Elizabeth, but a clause stated that she would forfeit her inheritance if she married an Irishman or a catholic. He bequeathed his extensive collection of law books to Trinity College Dublin library and made provision for a stipend for a librarian. Alexander was undoubtedly both ruthless and cruel, yet his will and the Breviate reveal a learned man of intellect and piety. In the Breviate he quoted extensively from both scripture and the classics, and (perhaps more revealingly) also referred to Machiavelli. There was a portrait of him in Kilcooly, with a Latin inscription translating as ‘No day without its work’.