A maverick preacher, known as Scotch Will, he was converted in the Scottish awakening of 1733-40. Of sturdy build and 'terrible to behold', he earned his living as a clogger and pedlar and became an itinerant evangelist in October 1741. From 1742 he was active on both sides of the Lancashire and Yorkshire Pennines, founding a number of societies which were brought under Methodist discipline in 1747, when Darney became a recognized Methodist itinerant on William Grimshaw's recommendation. In the Huddersfield area and elsewhere he faced fierce persecution at the hands of the mob.
After meeting him in Leeds in September 1751, Charles Wesley declared that Unless Darney would abstain from railing, begging, and printing nonsense, he should not be allowed to preach in any of the Methodist societies and preaching-houses. Darney had published A Collection of Hymns that year, which the Wesleys dismissed as doggerel and which led to Wesleys order, Sing no Persecutionhymns of your own composing. Print nothing without my approbation at the Conference of 1752 .
Grimshaw recognised his value as an evangelist and shielded him from the Wesleys' intermittent criticism of his Calvinistic tendencies evidenced in The Fundamental Doctrines which are contained in the Holy Scriptures (1755), his doggerel verse and general uncouthness. At the 1758 Conference the question Can we receive William Darney? received the reply, Not until we are fully assured that he does not rail, print, or sell wares without a license. While stationed in 1763 in East Cornwall, he came near to dividing the society at Plymouth Dock, leading Wesley to declare, I shall either mend William Darney, or end him. He must not go on in this manner. Eventually, when the 1768 Conference prohibited preachers from following a trade, Darney left the itinerancy and returned to the Rossendale area as a local preacher. He died in November 1774.
'A man of plain manners, - moderate talents; the author of many dogg[e]rel hymns, which greatly annoyed the good taste of Mr. Wesley Rather calvinistic in his creed; - fearless of danger; extensively useful.'
Wesleyan Takings (1840), p. 330
' When my father was once preaching in 1755 at Walmsley chapel, the enraged mob drove him into a pond of water, in the same way they would have done a beast. Also at Barrowford, the mob stripped him of his coat and took it to a dye-house, where they half dipped it in a working vat, literally making it a coat of many colours. At another time, at this place, they rode him through the deepest place of the river which runs through the village, one of the mob riding upon his back with a bridle about his head. They then procured a rope, which they fastened about his waist, and then fastening the rope to each side of the river, they literally tied him in the middle of the stream.
'In Colne the mob stripped him of all his clothes unto his naked skin, daubed him all over with mire, and drove him through the town streets in this condition.'
John Darney, quoted in J.W. Laycock, Methodist Heroes in the Great Haworth Round 1734 to 1784 (1909), p.114
,My companions in the east [of Cornwall, 1763] were Messrs Oldham, Darney, and Whitehead, who wre truly alive to God, and they were blessed to the people wherever they preached. Brother Darney had preached for years; he had been eccentric in his manner of labouring in the Connexion, and Mr. Wesley, with my brethren, thought I might be able to cure him. For a season he behaved pretty well, and was ready to be advised; but he relapsed into his former conduct, and advanced opinions in public contrary to the Methodist doctrine and discipline; so that we were obliged to call in a young man to labour in his place, and dismiss him from the circuit, and that by Mr. Wesley's express approbation. The greatest hurt he did was in the society at Plymouth Dock, where he nearly divided the people.'
Ibid, p.228, quoting Thomas Rankin