Fleetwood was probably just a few months old when his father granted him an annuity of £13 6s. 8d. in July 1560. As a younger son, his hopes of a more lavish patrimony were initially slim, and indeed he was bequeathed just £50 extra in his father’s will. However, under the terms of a family entail, he inherited four Buckinghamshire manors, including The Vache, when his elder brother Thomas died in around 1578. His marriage eight years later brought him valuable connections at Court, particularly with Lord Burghley (Sir William Cecil†) and Sir Francis Walsingham†, which doubtless enhanced his local standing. He first entered Parliament in October 1586, as Member for his local borough of Chipping Wycombe, served as county sheriff in 1590-1, and became a gentleman pensioner in around 1597.
Knighted shortly after James I reached London in 1603, Fleetwood was granted the presentation of a Canterbury prebend in May 1604, but that year he also received a less welcome Privy Seal loan demand for £30. He was returned to the first Jacobean Parliament for Tavistock, on the nomination of the 3rd earl of Bedford, his distant kinsman by marriage, whose seat at Chenies, Hertfordshire lay barely two miles from The Vache.
Religious affairs remained a major theme of Fleetwood’s performance during the second session, over the course of which he received 19 committee appointments. Named on 3 Feb. 1606 to a conference with the Lords on the recusancy laws, he was also nominated to scrutinize bills concerning the execution of these penal statutes, the regulation of ecclesiastical government and, once again, clerical pluralism (25 Feb., 5 Mar., 1 and 7 April). He was also appointed to the legislative committees for the attainder of the Gunpowder plotters, and the naturalization of the Scottish courtier Sir David Foulis, who had married his cousin Cordelia Fleetwood (18 and 30 April).
During his time as a gentleman pensioner, Fleetwood continued to reap some personal benefits. In 1607 he and three associates were granted a debt of nearly £12,000 owed to the king out of the estate of George Goring†, his brother William’s predecessor as receiver of the Wards. Two years later, he jointly leased a Buckinghamshire estate from the Crown for 21 years. He lost his position at Court around a decade into James’s reign, but still secured some favours subsequently, perhaps by purchase. In 1619 he was granted the right to hold a court leet for the manor of The Vache, and also a pension of £2,000 for life.
Fleetwood drew up his will on 20 Oct. 1620, confident of achieving salvation through Christ, who ‘hath, ever sithence I had any being, preserved me with a most fatherly and tender love amidst all the temptations of this wicked world, wherein ... I have lived a most sinful and ungodly life’. He provided six of his sons with annuities totalling £230 a year, and bequeathed £100 outright to the seventh, an apprentice. His two youngest daughters were each given portions of £500. As overseers he appointed his brother-in-law, Lord (Sir Edward) Denny*, and his cousin Sir William Fleetwood II*, the latter also being named as a trustee to raise the necessary funds from his estate. Fleetwood died two months later, and was buried at Chalfont St. Giles, as he had requested. His grandson George, who had inherited The Vache, represented Buckinghamshire in the Long Parliament, signed Charles I’s death warrant, and sat in the ‘Other House’ during the second Protectorate Parliament. As a regicide, he narrowly avoided execution after the Restoration, and forfeited his lands.