Besides being a merchant, he was a nonconformist, fellow of the Royal Society, diarist, author, common-councilman in the Corporation of Leeds, and museum keeper.
According to the preface of The Diary of Ralph Thoresby F.R.S., father and son were alike, deeply religious and both with strong attachments to antiquarian pursuits.
In 1690 Thoresby made the acquaintance of William Nicolson, an eminent antiquarian scholar and later Bishop of Carlisle, and from this point turned his mind towards the production of a history of Leeds and environs.
Throughout the last decade of the century, his fame as an antiquarian slowly rose, as did the public attention paid to his museum – an object of curiosity to strangers visiting the city.
He appears to have retired altogether from business in 1704, with a small income, and devoted himself to this museum, literary pursuits, and his religious observances.
It was asserted on page 90 in the 1927 book 'The Witching Weed', (Second Edition), George G. Harrap and Co., that from at least 1719, Thoresby " Carefully preserved in [his] museum..." Sir Walter Raleigh's tobacco box.
The Monthly Review for April 1830 was scathing about the publication: If the friends of sound and useful literature, and the enemies of these piles of trash, which, under the titles of 'Diaries' and 'Memoirs', have been for some years accumulating on the booksellers' shelves, were to pray for the publication of some work which would make manifest, even to the most stupid reader, the utter worthlessness of most of the volumes of this description which have recently escaped from the hands of the printer,—they could not have desired any occurrence more opportune for their purpose than the appearance of 'Ralph Thoresby's Diary'.
It exceeds both in quantity and quality of foolishness, any book of a similar description which has seen the light since the days of old Angelo, the fencing master.