Yorkshire for about six years, and apparently assisted Dr. Knowler in editing the 'Earl of Strafforde's Letters and Despatches,' 2 vols. 1739. In 1729 he wrote an 'Essay on Epistolary Writings, with respect to the Grand Collection of Thomas, earl of Strafford, dedicated to the Earl of Malton. While on a visit to Wentworth House he witnessed the wilful destruction of the collections of the antiquary Richard Gascoigne [q. v.], consisting of seven great chests of manuscripts [see Gascoigne, Richard, 1579-1661?].
On returning to London in 1730, Oldys discovered that Burridge had dispersed his books and papers. The former included Langbaine's 'Dramatick Poets,' with manuscript notes and references by Oldys. This annotated volume had passed into the possession of Thomas Coxeter, who, says Oldys in his second annotated copy of Langbaine, 'kept it so carefully from my sight that I never could have the opportunity of transcribing into this [volume which] I am now writing in the notes I had collected in that.' The book in question afterwards belonged to Theophilus Gibber [q. v.], and from the notes of Oldys and Coxeter was derived the principal part of the additional matter furnished by Cibber (or rather by Shiels) for the 'Lives of the Poets,' 5 vols. 1753, 12mo. To the 'Universal Spectator ' of Henry Stonecastle [see Baker, Henry, 1698-1774] Oldys contributed about twenty papers between 1728 and 1731. While in 1730 Samuel Burroughs and others were engaged in a project for printing the 'Negotiations of Sir Thomas Roe,' Oldys drew up 'Some Considerations upon the Publication of Sir Thomas Roe's Epistolary Collections' (now in the British Museum, Addit. MS. 4168).
Oldys had by 1731 brought together a valuable library. It contained 'collections of manuscripts, historical and political, which had been the Earl of Clarendon's; collections of Royal Letters, and other papers of State; together with a very large collection of English heads in sculpture, which alone had taken [him] some years to collect at the expense of at least three score pounds.' In the course of the same year he became acquainted with Edward Harley, second earl of Oxford [q. v.], who purchased for 40l., with the prospect of 'a more substantial recompense hereafter,' Oldys's collections, 'with the catalogues' he had drawn 'up of them at his lordship's request.'
Oldys had free access to Harley's celebrated library, and one result of his studies there was the publication of 'A Dissertation upon Pamphlets. In a Letter to a Nobleman' [probably the Earl of Oxford], London, 731 , 4to. It reappeared in Morgan's 'Phœnix Britannicus,' London, 1732, 4to, and in Nichols's 'Literary Anecdotes' (iv. 98-111 ). Oldys also contributed to the 'Phœnix Britannicus' (p. 65) a bibliographical history of 'A Short View of the Long Life and Raigne of Henry the Third, King of England : presented to King James by Sir Robert Cotton, but not printed till 1627.' According to Dr. Ducarel, Oldys wrote in the 'Scarborough Miscellany,' 1732-4. John Taylor, the author of 'Monsieur Tonson,' informed Isaac D'Israeli that 'Oldys always asserted that he was the author of the well-known song
Busy, curious, thirsty fly !
which first appeared in the 'Scarborough Miscellany' for 1732.
The London booksellers employed Oldys in 1736 to see through the press a new edition of Sir Walter Raleigh's 'History of the World.' To this edition (2 vols. 1736, fol.) is prefixed 'The Life of the Author, newly compil'd, from Materials more ample and authentick than have yet been published, by Mr. Oldys.' The 'Life' occupies 282 pages, and embodies much labour and research. It was reprinted in 1740, 8vo, and was prefixed to the collected edition of Raleigh's 'Works,' 8 vols. Oxford, 1829. Gibbon meditated a 'Life of Raleigh,' but he relinquished the design from a conviction that 'his ambition, exclusive of the uncertain merit of style and sentiment, must be confined to the hope of giving a good abridgment of Oldys' (Gibbon, Miscellaneous Works, 1837, p. 68).
The 'Life of Raleigh' greatly increased Oldys's fame. He was frequently consulted at his chambers in Gray's Inn on obscure and obsolete writers by eminent men of letters. He aided Thomas Hayward in compiling his 'British Muse,' and Mrs. Cooper in her 'Muses' Library,' and his jottings for a life of Nell Gwynne he gave to Edmund Curll. In 1737 Oldys published anonymously his 'British Librarian: exhibiting a Compendious Review or Abstract of our most scarce, useful, and valuable Books in all Sciences, as well in Manuscript as in Print: with many Characters, historical and critical, of the Authors, their Antagonists, &c., in a manner never before attempted, and useful to all readers,' London, 1738, 8vo. It was originally brought out as a monthly serial, in six numbers, from January to June 1737, though the postscript is signed 'Gray's Inn, Feb. 18, 1737,' i.e. 1737-8. The work contains curious details of works now excessively rare (cf. Dibdin, Bibliomania, ed. 1842, p. 52).