Myddelton was apprenticed to the London Goldsmith Thomas Hartopp in 1576, but after his master’s death in 1582 it was his elder brother, (Sir) Thomas Myddelton I*, who supported him, providing both professional commissions and the money to buy his freedom of the Goldsmiths’ Company in 1585. Myddelton’s second marriage was presumably also arranged by his brother, the bride’s stepfather. He reciprocated these favours by winding up (Sir) Thomas’s sugar business in Antwerp in 1585, and by arranging the latter’s investment of £150 in a privateering voyage organized by the Goldsmiths’ Company in 1589-90.
Myddelton established himself at a shop in Goldsmith’s Row on Cheapside, where he and Sir Walter Ralegh† allegedly popularized the use of tobacco by smoking together in his doorway.
For all his far-flung business interests, Myddelton maintained links with his native county. In 1597 he helped to secure a new charter for Denbigh, which named him as senior alderman, while a few years later he improved the town’s fuel supply by sinking coal mines nearby. Thus it was no accident that he looked to Denbigh Boroughs for a seat in Parliament from 1604. His quest was complicated by the fact that the franchise was shared between four boroughs. However, as one of these - Chirk - was dominated by his brother Sir Thomas, and he himself was appointed recorder of another - Ruthin - in February 1604, his return at the parliamentary election held in the following month was, perhaps, a foregone conclusion.
There is some difficulty in identifying Myddelton’s activities during the parliamentary sessions of 1604-14, as the surviving records do not always distinguish between him, his brother Robert*, and (in 1614) John Middleton. However, the relatively low profile Myddelton maintained in the House during the 1620s suggests that he was unlikely to have been particularly active during his first two parliaments. Either he or his brother moved for parliamentary privilege to stay a Chancery injunction in 1610, but most of the ten speeches made by ‘Mr. Middleton’ during the Addled Parliament, especially those concerning impositions and proposals to revoke the Merchant Adventurers’ monopoly of cloth exports, can be attributed to Robert, one of the City’s largest cloth merchants, with reasonable confidence.
While he represented a Welsh constituency, Myddelton took little known interest in the affairs of the principality, although he did sign the petition which was circulated at Westminster during the 1624 session opposing a lease of the Welsh greenwax fines to (Sir) Richard Wynn*.
It was probably in Parliament that Myddelton first encountered the New River scheme. On 31 Jan. 1606, he was named to the committee for a bill to supply water to London from Uxbridge or the River Lea. This project, sponsored by the Common Council, was radically altered in committee to give statutory authority to an existing patent allowing Edmund Colthurst to bring water from springs at Amwell in north-eastern Hertfordshire, in which form the bill duly passed into law. During the following session another statute was passed to endorse a rival plan to enclose the watercourse in a brick vault; Myddelton was also a member of the committee appointed to scrutinize this bill (1 May 1607). Colthurst ran out of funds at the end of 1608, whereupon the City offered the project to Myddelton, whose finances presumably inspired greater confidence, although he had private qualms about the magnitude of the project: ‘I have undertaken a matter ... that will cost me all my poor means’.
With the political future of the New River resolved, the Exchequer commission compounding for rights of way reconvened in January 1611, and construction resumed in the spring. Nine months later Myddelton reached the limits of his personal credit, having spent £1,100 upon a project which was experiencing technical problems and nowhere near finished. He appealed to Lord Treasurer Salisbury (Robert Cecil†) for assistance, and under a contract of 2 May 1612 the Crown took on half the costs and eventual profits of the scheme. The other half was divided into 36 shares, which were sold for £100 each to private investors.
One of the new Company’s first acts was to seek statutory confirmation of its charter, which contained a potentially controversial clause granting a veto over all other schemes to bring water to the capital. A bill was tabled in the Commons on 7 May 1621, not by Myddelton, who was then preoccupied with the Brading Haven drainage project and left no trace upon the records of the session, but by solicitor general Sir Robert Heath*. Despite this official support, the bill received only a single reading. It enjoyed a warmer reception in the 1624 session, when no less a figure than Sir Edward Coke* backed the committal of what he termed ‘a very good bill’, apparently because of Myddelton’s decision to open the river’s sluices to extinguish a fire in the City some months earlier. However, the committee never reported its findings, while a subsequent attempt to introduce the bill into the Lords got no further than a first reading (11 Feb. 1626).
Despite its heavy demands upon his time and capital, the New River Company was only the beginning of Myddelton’s entrepreneurial exploits. While the project was undoubtedly a major drain on his personal resources during its construction phase, most of his original outlay was recouped from Crown, shareholders and the City’s loan in 1614-17. Thus flush with cash, it was hardly surprising that he should be found casting around for other investment opportunities over the next few years. The first was a lease of the Crown’s mineral rights in northern Cardiganshire, which had fallen into ruin after the previous tenant, Sir Lewis Lewknor*, became entangled in title disputes.
The final project in which Myddelton became involved was the drainage of Brading Haven at the eastern end of the Isle of Wight. The right to reclaim this land had been assigned to a Scottish courtier in 1616, but Bevis Thelwall brought the patent to Myddelton’s attention, and in 1620 the pair joined with Sir Eubule Thelwall* in a partnership to exploit this grant. The Thelwalls put up most of the £2,000 required to buy out the patent and the Crown’s right to recovered grounds, while Myddelton, who held a controlling four-sevenths share in the enterprise, provided another £3,700 to perform the drainage work.
Myddelton continued sparring with the Thelwalls in the courts for the remainder of his life, although his chances of overturning Sir Eubule’s arbitration were slim, as the latter was a master in Chancery. It eventually emerged that Thelwall had discounted the price his brother paid for Brading first to allow for Myddelton’s repurchase of the Thelwalls’ four shares in the Cardiganshire mines, and secondly to account for the 1,000 marks Myddelton was said to have promised Sir Bevis for procuring his baronetcy in October 1622. The former point was a mere actuarial calculation, but the latter was a calculated slur upon Myddelton’s reputation, as it had always been said that he obtained his baronetcy free of charge, ‘for his good service in bringing the water to London, and finding out the silver mine in Wales’. Sir Bevis never claimed that the Crown had levied its normal charge of £1,095 for the honour, but he did insist that Myddelton had secretly given him £50 to distribute to Household officials who would normally receive fees for such a grant. Furthermore, once the patent was passed, it was arranged that Thelwall should bring it unannounced to a dinner at Myddelton’s London house, where, to the host’s feigned astonishment, this signal mark of royal favour was revealed to the assembled company. Myddelton grudgingly agreed that the tale about the dinner was true, but was ultimately to have the last laugh on his tormentor, as the Brading embankment was destroyed by a storm in 1630, and Thelwall’s lands reverted to the sea.
During the last year of his life Myddelton rearranged his business interests. In March 1631 he mortgaged his Denbighshire estates to his brother Sir Thomas for £6,000. This sum was presumably used to purchase the Crown’s 50 per cent interest in the New River Company, which was granted to him on 18 Nov. 1631, albeit charged with a perpetual annuity of £500.
Myddelton’s estate settlement gradually unravelled in the decade after his death. His widow quickly sold his Welsh lands to Sir Thomas Myddelton II* for £2,000, but held on to the Cardiganshire mines, which were apparently dilapidated by the time she leased them to the entrepreneur Thomas Bushell for £400 a year in 1636.