Osborne’s grandfather and namesake, a younger son from Essex, founded his family’s fortune by obtaining an Exchequer office - that of lord treasurer’s remembrancer - which became hereditary. He bought Chicksands in 1576, and sat in seven Elizabethan Parliaments. Osborne’s father, Sir John, nearly matched this record, participating in six sessions.16 HP Commons, 1558-1603, iii. 157-8; G.E. Aylmer, King’s Servants, 283-4; VCH Beds. ii. 271. In June 1604, possibly while still at university, Osborne was granted the reversion to the remembrancer’s office, but it would be another 24 years before he took charge. In 1617 he accompanied Sir John Digby* to Spain. Four years later, he became deputy and reversioner to his brother-in-law, Henry Danvers, 1st earl of Danby, as governor of Guernsey, and took up residence at Castle Cornet.17 Lansd. 1217, f. 72; SP94/22/241; Kimber and Johnson, ii. 151; Oxford DNB.
Osborne was returned for Corfe Castle in 1624, perhaps on the recommendation of one of the borough’s previous Members, Sir Thomas Hatton, who was later one of his trustees.18 PROB 11/236, f. 264. He made no known speeches, and was appointed only to help scrutinize a bill to confirm a purchase of lands by Sir Thomas Cheke*, whose first wife was Osborne’s aunt.19 CJ, i. 680a. Re-elected in 1625, he spoke on behalf of the Exchequer’s officials in a debate on the bill for ease in pleading of alienations, asking for them to be heard by counsel before the committee, and to be given time to prepare their case and produce records (25 June).20 Procs. 1625, p. 246.
In 1628 Osborne succeeded his father as treasurer’s remembrancer, but he continued to spend most of his time on Guernsey. Upon the outbreak of the Civil War, he held Castle Cornet for the king, but in 1646 he handed over command to (Sir) Thomas Fanshawe II*, and went into exile in France. He compounded for his delinquency in 1650, paying £3,737.21 Oxford DNB; Hoskins, i. 390; CCC, 1974. Osborne made his will on 26 Feb. 1650. Clearly conscious that he was part of a dynasty, he specified that certain of his grandfather’s old furnishings at Chicksands were to be preserved there as heirlooms. ‘A friend to the poor, a lover of learning, a maintainer of divine exercises’, he was buried nearby at Campton, Bedfordshire in March 1654, aged nearly 69.22 PROB 11/236, f. 264; F.A. Blaydes, Genealogia Bedfordiensis, 61; Coll. Top. et Gen. iii. 124-5. His son John was created a baronet at the Restoration and regained the remembrancer’s office, while his daughter Dorothy achieved fame as a letter-writer. However, no further members of the family entered Parliament until Sir Danvers Osborn was returned for Bedfordshire in 1747.23 Kimber and Johnson, ii. 151; Exchequer Officeholders, 56; Oxford DNB.