The Society for Constitutional Information aka The Constitutional Society had been active since 1770s. Over time it had branches in most major towns in England, especially in the North, e.g. Stockport, Manchester, Sheffield. There were branches in Derby and Nottingham.
Manchester Constitutional Society was formed 1790. A founding member was Thomas Walker (b. 1749), a cotton merchant. He was active in the movement for abolition of the slave trade and was an organiser of the Manchester anti-slavery group. He was also a member of Friends of the People, another group for political reform. Repeated mob-violence against his home led to him and his friends arming themselves for protection. He was arrested and put on trial at Lancaster in 1794.
Leeds Constitutional Society claimed to have 2000 members in 1793. Sheffield Constitutional Society had "several thousand". ("The British Democrats" page on
https://www.marxists.org/history/england/britdem/index.htm )
This website has information about other reform and radical movements.
The London Corresponding Society became the largest radical organisation in England. It collected names on a petition for electoral reform in April 1793. Three pamphlets published by the society are in the British Library including "Address of the London Corresponding Society, to the other Societies of Great Britain, united for obtaining a Reform in Parliament", published 1792.
https://www.bl.uk/collection-items/address-of-the-london-corresponding-society-for-obtaining-a-reform-in-Parliament"Parliament and the London Corresponding Society", a thesis by Reed Joseph Vandehay, Portland State University 1975
https://core.ac.uk/download/pdf/37774413.pdfThe Friends of the People had only a small membership in England but was the dominant organisation in Scotland.
A British Convention in Edinburgh in 1794 was attended by some English radicals.
Spartacus Educational website has a section on parliamentary reform.
https://spartacus-educational.com/PRparliament.htmThere are numerous sub-topics and bios of key players.
My interest in the London Corresponding Society led from learning about Ned and Kitty Despard after seeing them in "Poldark". They could have a spin-off series. There is an illustration of the petition for reform in Parliament in an article about Edward and Catherine Despard. There is also a portrait of Olaudh Equiano, another member of the society. Catherine Despard became a campaigner for prison reform as a consequence of her husband's imprisonment.
https://mikejay.net/edward-and-catherine-despardThe sentence on Edward Despard and his co-conspirators, and on some later agitators was to be hanged, drawn, quartered and beheaded, since they had been found guilty of treason. The punishment was commuted to hanging and beheading, omitting disembowelling and quartering.
History Workshop is a website I've just discovered. It has information about the London Corresponding Society.
www.historyworkshop.org.uk