He had little success as a barrister, but was employed by Sir John Parker Mosley, 1st Baronet as steward to the Manchester manorial court.
Writing to William Cavendish-Bentinck, 3rd Duke of Portland, the Home Secretary, Hay reported that the meeting had been peaceful, the magistrates had had no specific intelligence, and seditious intent would be hard to prove.
[8] Later that month, as part of the same campaign of 1800–1 to close down public expression of disaffection on the border between Lancashire and Yorkshire, Hay with another magistrate dispersed another meeting near Buckton.
Hay's comment to the Home Office stated again that the meeting was peaceful and seditious intent would be hard to establish; but argued expediency.
[9] In 1803 Hay was elected chairman of the quarter sessions for Salford Hundred, succeeding Thomas Butterworth Bayley, who had died in 1802; at this point he had been a justice of the peace in the West Riding of Yorkshire, Lancashire and Cheshire for some years.
[7][10][11][12][13] Bayley, Hay and Thomas Bancroft, vicar of Bolton, formed a discriminating group gathering local intelligence and showing scepticism to claims of their spies and informants, whom they recruited carefully.
[14] In 1812, at the time of the disorder at the Manchester Cotton Exchange and the reading of the Riot Act by two magistrates (Silvester and Wright), Hay found an ally in Charles Ethelston.
[15] In 1818 Hay was deprecating to Henry Hobhouse of the Home Office the reluctance of manufacturers to use the Combination acts against strikers in the cotton industry who were attacking factories, putting it down to fear.
[19] Present as a magistrate on 16 August 1819 at Peterloo, Hay wrote the letter of that evening to Lord Sidmouth giving an account of the events, James Norris being "very much fatigued by the harassing duty of this day".
[21] In October 1819, Hay attended a dinner given by Lord Liverpool, the Prime Minister, where he was treated with high regard by Sir John Copley, the Solicitor General.
[7][25] Hay continued to hold the Ackworth rectory with a dispensation;[26] he had curates there, William James Farrington (1820), John Hope (1821), Richard Bassnett (1823), and Thomas Frederick Paull Hankins (1828).
[32] He was briefly back in court in 1825, and not in a good temper, after Starkie resigned, for a right of way case involving the magistrate Ralph Wright, at Flixton.
[33] At Rochdale, Hay was still active in local politics in the last summer of his life, extending the hustings on a vote affecting church rates.
His obituary in the Gentleman's Magazine compared Hay's role at Peterloo with that of Sir Thomas Phillips in the recent Newport Rising.
The pamphlet collection was purchased by Charles Winn (1795–1874) from Barclay in 1839 and is now in the library at Nostell Priory,[45] owned by the National Trust.