One of only four Members returned to every Parliament from 1601 to 1628, Killigrew invariably held a Cornish seat, although he switched constituencies at each election, representing only one borough twice. This local dominance, which also made him one of the leading electoral patrons of this period, is the more remarkable because he owned comparatively little land in Cornwall, and spent most of his life at Court. In effect, he successfully built on the foundation laid by his father, Sir William, who, through his long-standing position in the privy chamber and his kinship with the Cecils, established his reputation as ‘the most kind patron of all his country and countrymen’s affairs’ in London.
Killigrew’s career outside Parliament proved more eventful. In 1605 he secured the reversion of one of Sir William’s main sources of income, the farm of the profits of the seal office in King’s Bench and Common Pleas. Shortly afterwards he joined the earl of Nottingham’s embassy to Spain, where he was falsely rumoured to have died in a duel with Sir Robert Drury*, sometime antagonist of his brother-in-law, Sir William Woodhouse*.
In 1614 Killigrew began to flex his muscles as an electoral patron, relying on a combination of his father’s Cornish estates and his own Launceston Land stewardship. At Helston, where he secured his own return, he offered the other seat to his friend James Whitelocke*, then accepted the latter’s nomination of Henry Bulstrode. A distant cousin, Sir Thomas Cheke, was found a place at Newport, alongside Thomas Trevor, whose brother Sir John Trevor I* had accompanied Killigrew on the 1605 embassy to Spain. Francis Crane at Penryn, Sir Charles Wilmot and William Croft at Launceston, and Robert Naunton at Camelford, were probably all presented to their respective boroughs by Killigrew at the request of Rochester, now earl of Somerset.
In July 1614 Killigrew exchanged his pension for the reversion of the captaincy of Pendennis Castle. Besides strengthening his influence over the borough of Penryn, this appointment will have had considerable resonance in Cornwall, because his family had monopolized the post until John Killigrew† of Arwennack was deprived for misconduct in 1598.
The 1620 parliamentary elections in Cornwall were complicated by the nominations which a number of boroughs received from Prince Charles’s Council. Newport and Helston were both affected, though Killigrew took the remaining seat in the former, and successfully nominated his friend Sir Thomas Stafford at the latter. Penryn, which would shortly choose Killigrew as its recorder, returned his nephew, Robert Jermyn, and once more accommodated Sir Francis Crane. During the 1620s Bodmin also came under Killigrew’s sway, for reasons which are unclear, and Sir John Trevor I’s presence there may have been the first sign of this phenomenon.
In November 1621 Killigrew was approached by the earl of Southampton to invest £100 in the troubled Virginia Company, but seems to have held back out of concern over its future. In the following February he was summoned before the Privy Council for refusing to contribute £100 towards the Palatinate Benevolence. His objections are unlikely to have been ideological, as just a few weeks later he requested the queen of Bohemia to use her influence to secure his second son a place in the prince of Orange’s service. He may have been experiencing financial difficulties, though these will have been eased by his father’s death in November 1622, which markedly increased his landed income and also brought him the profits of the seal office.
At the 1624 general election Killigrew took the first seat at Penryn for himself, and handed the other to a Middlesex neighbour, Edward Roberts. Bodmin similarly accepted two nominees, his friend Sir Thomas Stafford and his nephew Sir Charles Berkeley. Killigrew may also have used his Launceston connections to secure a place there for Sir Miles Fleetwood, as a favour to Buckingham. However, at both Helston and Newport he seems to have lost out to a strong showing by more local patrons.
In June 1624 Killigrew was named to the commission for settling the government of Virginia. However, with war now a real prospect he was more preoccupied with events at home. In October he obtained a privateering licence from Buckingham, and in the following month secured a fresh supply of arms for Pendennis. In April 1625 he finally persuaded the Council of War to provide another £350 for repairing the castle, while his role as a Cornish commissioner for impressment placed him at the heart of local military preparations.
Around early August 1625 Killigrew secured the nomination to replace Sir Dudley Carleton as ambassador to the United Provinces, apparently in the hope of reducing ‘the incommodity of his estate’. However, although his official payments began in the following December, it emerged that he was unacceptable to the Dutch, partly perhaps because of his long-standing association with Arminians such as Richard Thomson. With the States threatening to withhold the privilege of admitting the English ambassador to their councils, the king conceded defeat in November 1626 and dispatched Carleton back to the Hague, though Killigrew was still being paid as late as March 1627.
This personal setback had no apparent impact on Killigrew’s standing in Cornwall, and at the 1626 general election his patronage was undiminished. Penryn once more elected Edward Roberts and Sir Edwin Sandys. Henry Jermyn retained his seat at Bodmin, though Sir Henry Hungate was shifted to Newport. Jermyn’s partner this time was another Buckingham client, Sir Richard Weston, while Edward Lyndsey was probably nominated at Camelford as a favour to the 4th earl of Dorset (Sir Edward Sackville*). Killigrew himself found a place at Tregony, conceivably by arrangement with Charles Trevanion, his fellow knight of the shire in 1625. His status as one of Buckingham’s more prominent clients placed him on the defensive throughout the 1626 Parliament. On 22 Feb. he failed in a bid to postpone discussion of the second arrest of the St. Peter of Le Havre. Appointed on 1 Mar. to deliver to the duke the Commons’ request for an explanation of this incident, he reported back the next day that this direct approach had caused offence in the Lords as a breach of parliamentary etiquette. His advice that the normal procedures be followed was ignored, and on 4 Mar. he was named to the conference where the two Houses debated whether Buckingham’s privilege had been infringed.
Killigrew’s firm support for the Forced Loan of 1626-7 requires little explanation. Although the onset of war underlined the strategic significance of Pendennis, he had been unable to obtain further funding for essential repairs since early 1625. By the spring of 1626 he was paying the garrison himself, and in January 1627 he complained to the Privy Council that he had now petitioned 69 times since assuming the command. In February the Council accepted Killigrew’s proposal that £1,177 of Cornish Loan money should be spent on repairing Pendennis, and in September it provided a further £300 from the same source. However, his consequent concern that the Loan should be collected efficiently did not guarantee his co-operation with Buckingham’s other principal West Country client, (Sir) James Bagg II*. In June 1627 he complained to Sir Edward Conway I* that Bagg was interfering in his naval jurisdiction at Falmouth, acting as though he were the duke’s sole mouthpiece in the county, and threatening ‘that he would use [Killigrew] as he did others’.
Not surprisingly, when Bagg’s Cornish allies, led by John Mohun*, attempted to prevent Sir John Eliot and William Coryton from standing as knights of the shire in the 1628 parliamentary elections, Killigrew stood aloof, and focused on finding seats for his own circle. In fact, the growing hostility of voters towards Buckingham and his clients seems to have limited Killigrew’s options this time. He himself was returned at Bodmin, but the other seat there went to Coryton’s ally Humphrey Nicoll. Killigrew successfully nominated Sir Thomas Edmondes at Penryn and probably Evan Edwards, another of Dorset’s servants, at Camelford. However, he was sufficiently unsure of his own authority that his heir, Sir William Killigrew II, stood at both Newport and Penryn, eventually opting to represent the latter borough after the legitimacy of his election at Newport was questioned. Killigrew played little part in the 1628 parliamentary session, making just three speeches. On 4 Apr., with Eliot trying to delay a vote on supply, he called for a division to settle whether or not the king’s financial propositions should be discussed first. When the Commons debated on 3 June how to respond to Charles’s unsatisfactory first response to the Petition of Right, he argued that the king would be more co-operative if Members completed work on the subsidy bill. On 9 May he was added to the select committee which considered the contempt of John Mohun and his faction in ignoring the Commons’ summons to explain their behaviour during the Cornish shire election. Killigrew headed the committee list on the bill for the restitution in blood of Carew Ralegh (4 June). His other legislative committee appointments related to the naturalization of his son-in-law, George Kirke, and saltpetre production (26 Apr. and 27 May).
In March 1628 Killigrew had obtained a fresh grant of the Pendennis captaincy, which handed joint command to his son Sir William. This enabled him to spend more time in London, and four months later he was appointed vice-chamberlain to the queen. In the same year he succeeded Francis Carew I* as prothonotary of Chancery, though he held this office only for the benefit of Carew’s mother.
Killigrew made his will on 12 Sept. 1632, his Arminian reputation belied by his decision to copy his father’s Calvinist religious preamble. In keeping with his social standing, he allowed for £100 to be spent on his funeral. To his wife he left his main seat of Kempton Park, so long as she remained unmarried, along with a share of the seal office profits. He provided £1,500 dowries for his three unmarried daughters, and divided his fenland investments between his sons and some of his servants. His patent of Irish starch, obtained in reversion in 1629, would shortly come into force, and he assigned the profits to paying his debts and legacies. His designated overseers were his friend Stafford (who later married his widow), Sir Benjamin Rudyard* and Robert Long*. Killigrew drew up a separate codicil on 24 June 1633, taking account of his most recent fen drainage project. He died shortly afterwards, and was buried on 3 July at St. Margaret Lothbury church in London. His main will was proved on 12 July 1633, the codicil five years later.