Herbert’s father, second son of the 1st earl of Pembroke, was granted the manor of Hendon, Middlesex and various properties in Pembrokeshire and Glamorgan upon his marriage in 1569. A decade later he acquired the lordship of Powis, Montgomeryshire, comprising some 150,000 acres of upland pasture, from Edward Grey, illegitimate son of the last Lord Grey of Powis. He may be assumed to have obtained a good price, as the vendor’s title was then being contested by Henry Vernon of Stokesay Castle, Shropshire, descendant of a daughter of the 1st Lord Grey, who pursued his cause vigorously in Parliament and the law courts. Although warned to desist by both Vernon and the Privy Council, Herbert pressed ahead with his purchase, and in 1587, shortly after his brother’s appointment as lord president in the Marches, he made good his title to the estate.
William Herbert was acknowledged as heir to the Powis estate in his father’s inquisition post mortem of 1595, but Vernon made a final bid for control with a private bill given a first reading in the Commons on 13 Apr. 1604, which proposed to overturn a fine levied at the Montgomeryshire Great Sessions in 36 Henry VIII, whereby the descent of the lordship was settled upon Edward Grey. This fine (upon which the Herberts’ title depended) had come into question in 1579, when Grey’s cousin Sir John Throckmorton† was sacked as justice of Chester and fined 1,000 marks in Star Chamber for returning a false certificate of the damaged original into King’s Bench. Yet the fine itself had been confirmed, a situation Vernon aimed to overturn with his estate bill. Counsel was heard for both sides, but at the second reading several MPs feared that a revocation of the original fine would prejudice a fresh hearing of the case in the courts, and on 4 May 1604 the bill was rejected by 202 votes to 130. The controversy ended with Vernon’s death in July 1606.
Control of the Powis estate also brought the Herberts into conflict with their neighbours, the Vaughans of Llwydiarth, who held 120,000 acres in northern Montgomeryshire. The two families sustained a protracted quarrel over 4,000 acres of common land near Llwydiarth, which quickly spilt over into local politics. Thus the Vaughans supported Arthur Price†, the Herberts’ opponent at the hard-fought county election of 1588, while in 1602 the rival factions clashed over control of the borough of Llanfyllin. Later the same year the Vaughans successfully petitioned against Herbert’s plans to secure the shrievalty of Montgomeryshire for himself or one of his relatives. Matters took an unexpected turn in 1616, when Owen Vaughan, apparently distracted by the execution of a cousin for the murder of one of Herbert’s servants, committed suicide. The Llwydiarth estate escheated to Herbert as lord of Powis, who waived his rights in return for a marriage between his daughter Katherine and Robert Vaughan, heir to Llwydiarth, an arrangement which left a legacy of resentment among Vaughan’s younger brothers.
Herbert’s return as knight for Montgomeryshire in 1597, only a few weeks after the death of Arthur Price, signified the resumption of the Herberts’ domination of county politics. The only likely alternative as MP was Herbert’s fourth cousin (Sir) Edward Herbert* of Montgomery, who replaced him at the next election. In 1604 Sir William, seeking election to co-ordinate opposition to Vernon’s estate bill, was returned for the shire once again. Sir Edward, who voluntarily assigned his interest in the Montgomeryshire seat to his cousin, spent much of the next 20 years abroad as a soldier and a diplomat, leaving Sir William to represent the shire throughout the period. For all his local status, Herbert accomplished little in the first Jacobean Parliament beyond blocking Vernon’s bill: he was named to four bill committees and ordered to attend two conferences with the Lords, and on 29 Nov. 1606 he was added to the committee preparing for a conference over the Instrument of Union.
At the start of the Addled Parliament Herbert was named to the important committee investigating the ‘undertakers’ who were alleged to have offered to manage the Commons for the Crown (13 Apr. 1614). A month later there were complaints that he had accused the committee chairman, Sir Roger Owen, of partiality. He held a longstanding grievance against Owen, who had supported Vernon over the Powis lordship dispute, and one diarist noted that Herbert,
being a man of an haughty spirit, rose up and accused himself and confessed that he told him [Owen] that he dealt partial in his judgment and moreover professed that he should love him the worse for that business so long as he knew him. Whereupon he [Herbert] made his recantation openly for those words and ... went out [of the House] voluntarily.
This act of contrition proved just sufficient to save Herbert from expulsion.
Although a fixture at the Jacobean Court, Herbert maintained a low political profile during the first half of the reign, perhaps the price he paid for his strong Catholic connections in the aftermath of the Gunpowder Plot: his mother was a notorious recusant, as was his wife, a sister of the 9th Earl of Northumberland.
Herbert’s significance in Parliament during the 1620s owed much to his links with Pembroke, but he never aspired to the stature of the earl’s regular parliamentary mouthpiece, Sir Benjamin Rudyard. Pembroke had been one of the original backers of George Villiers, marquess (and later duke) of Buckingham, but by 1621 he was willing to see the wings of the now over-mighty favourite clipped. Herbert therefore added his voice to the clamour raised in Parliament against monopolists, most of whom were linked to the Villiers clan. In a debate of 6 Mar. on the gold and silver thread patent he urged an enquiry as to the origins of the bullion used by threadmakers. Two days later, the Commons’ rehearsal of the charges against the patentee (Sir) Giles Mompesson*, was terminated by Speaker Richardson, who left the House without warning, unsettling those who were to deliver the charges to the Lords a few hours later. On the following morning Herbert chided the Speaker `that he was required by the greatest voice of the House to sit still. That he must respect the meanest, as well as those about the chair [i.e. Privy Councillors]’. On 21 Mar. (Sir) Robert Lloyd*, whose patent for engrossing of wills had come under attack, protested that he was not the original promoter of the project; Herbert refuted this claim, and, for good measure, added that he had heard the king himself ‘more inveigh against this patent than ever [he] did against any other’. Yet Lloyd was not the only courtier to benefit from monopolies: when Herbert was linked with Sir Robert Mansell’s* glass patent, he sheepishly explained that he had acquired his share as settlement for a debt.
Whatever his grievances against monopolists, Herbert was careful not to trench upon the prerogative: learning that Sir George Marshall’s* lawsuit for payment of 1,000 marks for procurement of a knighthood was based on a Chancery decree secured upon a letter from James, he insisted that the sentence be razed from the record `to clear the king’s honour’. On 4 May 1621, when the king questioned the Commons’ claim to pass judgment upon the Catholic barrister Edward Floyd for slandering Princess Elizabeth, Herbert observed that execution of sentence lay with the king, while over the following fortnight he attempted to avert a jurisdictional dispute with the Lords over this case. Unlike some Members, Herbert wished to see a successful conclusion to the session, and therefore his forays into the realm of high politics, although rare, were constructive. On 22 Mar., he was among those who supported the king’s unsuccessful request for an abbreviated Easter recess, while at the end of May, when James caught the Commons unawares with his insistence on an early adjournment, he was disinclined to pick a quarrel: ‘let us leave all with prayer to God for his blessing to our next meeting’.
In the 1624 Parliament Herbert followed the semi-official brief of the ‘patriot’ coalition assembled by Buckingham and Prince Charles to press the king for an end to the pro-Spanish policies of the preceding 20 years. Among the patriots, Pembroke was the keenest to use Parliament to make a formal breach with Spain, and it is hardly surprising that his cousin should have played a role in these plans.
While Herbert often spoke to Pembroke’s brief in Parliament, he was equally capable of promoting Welsh interests, particularly those relating to the upland economy of Powis lordship. One of the prime movers of the 1621 bill to break the Shrewsbury Drapers’ monopoly of the Welsh cloth trade, he complained vehemently to the Company’s lobbyist about the Salopians’ boycott of the cloth market at Oswestry, and rejected offers to come to a settlement. Herbert was not recorded to have spoken in the extensive debates, but he attended one of the two committee meetings and probably continued to provide leadership for the Welsh clothiers after the dissolution of the Parliament, as the compromise which finally settled the issue in the spring of 1623 was sealed by the admission of Herbert and his son as freemen of Shrewsbury.
Herbert’s chief concern outside Parliament in the 1620s was the fate of the Llwydiarth estate: his son-in-law Sir Robert Vaughan died suddenly on 2 July 1624, while the latter’s widow, Dame Katherine, gave birth to a son, Herbert Vaughan, three weeks later. However, by then Sir Robert’s brother Edward Vaughan* had taken possession of Llwydiarth under an entail drafted on 2 Feb. 1622 at his behest, which had ignored the claims of Sir Robert’s wife or any future male heir. This entail was too obviously convenient for Vaughan’s purposes to be credible, as was the additional claim that Herbert Vaughan was a changeling, substituted at birth for the girl Dame Katherine had allegedly delivered. Vaughan made desperate attempts to bolster his position through an offer of marriage to the Villiers clan, but although he elicited a sympathetic letter from the favourite’s mother to lord president Northampton, the Council in the Marches awarded Dame Katherine an injunction to put her in possession. Herbert was later said to have mustered the militia to eject Vaughan from Llwydiarth, resulting in a violent affray during which one of his servants was killed.
At the 1625 general election Vaughan almost certainly contested the Montgomeryshire seat, prompting Herbert to apply to Pembroke for a safe seat at Wilton, which ultimately proved superfluous. For all this effort, Herbert played little part in the proceedings of the session: he was named to the privileges’ committee (21 June); ordered to attend two conferences with the Lords (23 June, 8 July); and included on a delegation sent to Charles with a petition for stricter enforcement of the recusancy laws (8 July), presumably because of his position in the Household. Parliament quickly adjourned to Oxford because of the plague raging in London, but Herbert may have stayed away, as he left no further mark on the records of the session. His diffident performance doubtless owed much to Pembroke’s reluctance to make an open demonstration of his growing antipathy to Buckingham.
Herbert was probably returned unopposed for Montgomeryshire in 1626, but Vaughan found a seat in neighbouring Merioneth, and attempted to have Herbert included on the recusant officeholders’ list on 3 May, a motion ignored by a Commons which needed Pembroke’s support for its impeachment of Buckingham. Herbert’s role in the impeachment debates was surprisingly modest, as Sir James Bagg II* noticed, remarking that ‘the earl of Pembroke ... doth appear publicly rather by strangers than by Sir Benjamin Rudyard, Sir William Herbert and others of his’, a tactic which allowed the earl the option of a reconciliation with the duke in the event of failure.
Immediately after the dissolution of June 1626 Pembroke was reconciled to the duke and appointed lord steward, although he lost much of his influence on the Privy Council during the collection of the Forced Loan. Herbert also kept a low profile, while his son Sir Percy* served as a collector for the Loan.
Herbert appeared only once more in the debates on the Petition, on 22 May, as the Commons threw out the Lords’ proposal to add a clause to the Petition saving the king’s prerogative. The debate was held in closed session, with no-one allowed to leave the House, but at one point it was noted that Herbert had slipped away - doubtless to warn Pembroke of the failure of the Lords’ initiative - and the serjeant-at-arms was sent to find him. The Lords quickly capitulated, and the Petition was sent for the Royal Assent unaltered. To encourage Charles, the Commons resumed debate upon the long-delayed subsidy bill, but when the king’s expected response failed to materialize, the House held up the bill again with an heroic filibuster on 31 May. Towards the end of this debate Sir Thomas Jermyn optimistically suggested completing the first reading of the bill, but his motion was cast aside by Herbert: ‘Wilfulness and perverseness have caused this long dispute; when there is not a yielding to reason all goes awry. I think we may rise, and without prejudice to the king’s service’.
Herbert was also involved with a selection of other business during the session, including two committees investigating the misconduct of Buckingham’s allies in Cornwall (20 Mar., 16 Apr.) and another to examine the new book of customs rates drafted by Sir Edmund Sawyer* (17 May), one of the trustees for Sir Percy’s wife. On 5 May, Herbert claimed that a clergyman who had written a mock catechism lampooning puritans had been advised to keep silent under questioning, providing some brief amusement by casting his speech in the same didactic form as the minister’s libel. He was once again obliged to present himself as a recusant officeholder because of his wife’s Catholicism, but was excused by the House. Finally, in the closing days of the session, his Court contacts proved useful in arranging several meetings with the king to smooth the passage of business.
Buckingham’s assassination was followed by a jockeying for position on the Privy Council between supporters and opponents of war. Herbert sought to bolster the position of Pembroke, chief among the hawks, by effecting an alliance between his patron and Sir John Savile, whose rival Wentworth had longstanding links with the key peacemaker, lord treasurer Weston. War was not possible without parliamentary subsidy, and Pembroke’s faction were thus keen to remove potential sources of conflict in the parliamentary session of 1629. Hence when a motion was tabled for an investigation of the king’s interference with the printing of the Petition of Right, Herbert protested that ‘this comes near the Spanish Inquisition to make particular inquisitors’, an inflammatory turn of phrase for which he was called to order by (Sir) John Eliot.
Pembroke’s death in April 1630 deprived Herbert of his chief patron, and his relationship with the earl’s brother, lord chamberlain Pembroke and Montgomery, while close, was punctuated by a series of quarrels, particularly when Montgomery suggested that Sir Percy Herbert’s son should be taken away from his parents and raised in a Protestant household.