Cooper was born in
Westminster, England. In 1779, he matriculated at
University College, Oxford, but did not graduate, supposedly refusing the religious test. He then qualified as a barrister being admitted to the
Inner Temple in 1779 and called to the bar in 1787. He also studied medicine and the natural sciences. He travelled the Northern Circuit practising as a barrister from 1788 to 1790. At the same period he went into the
calico printing business at Raikes near
Bolton,
Lancashire. Cooper took on a prominent role in the reforming politics of the time. In early 1790 he took part in the campaign by
Dissenters for greater religious tolerance. His approach was considered too extreme by some, and he shed much moderate support after a meeting in
Cheshire.
Edmund Burke mentioned Cooper in the House of Commons in March of that year. In October 1790 the Manchester Constitutional Society was set up, with Cooper, author of
Letters on the Slave Trade (1787), and other members such as
Thomas Walker, noted as radicals and
abolitionists. The Constitutional Society had members in common with the
Manchester Literary and Philosophical Society. But in July 1791 the
Priestley Riots took place, driving
Joseph Priestley from his home. The whole radical group resigned
en masse, in 1791, when the Literary and Philosophical Society refused to send Priestley a message of sympathy. He was elected a Member of the
American Philosophical Society in 1802. In the rapid developments stemming from the
French Revolution, Cooper was sent to Paris in 1792 with
James Watt Jr., by the Constitutional Society of Manchester. They travelled with an introduction from Walker to political circles through
Jérôme Pétion de Villeneuve, and another to a man of science,
Antoine Lavoisier, from Priestley. Cooper was for some purposes a representative of the British democratic clubs to those of France, but the situation on both sides of the Channel was by now becoming complex. The Manchester group favoured the
Jacobins in the emerging split with the
Girondins. Edmund Burke again censured Cooper in the House of Commons, and Cooper replied with a vehement pamphlet. Cooper came to represent the
Society for Constitutional Information (SCI) alone, in dealings with the Jacobins. The Whig
Friends of the People took steps to exclude him, out of concerns that its membership should not overlap with that of the more radical SCI: Burke had called the Manchester reformist group "some of the worst men in the kingdom" to score a political point off
Charles Grey, who had been instrumental in setting up the Friends in April 1792. While in France Cooper learned the process of obtaining
chlorine from
sea salt. He tried to apply this knowledge on his return to England to
bleaching of textiles, but was unsuccessful. By 1793, Cooper became disillusioned with the violent course of events in France. Both he and Watt later represented themselves as always favouring moderate elements (which is doubted now by scholars). But Cooper was in some danger of prosecution at home because of his views. He ruled out France as a destination, and made a preliminary journey to the
United States in early 1794. ==First years in the United States==