Papers, missing for more than 200 years, have been unearthed which shed new light on the tumultuous life of the Scottish political reformer, Thomas Muir.

Discovered by the Faculty of Advocates and Professor Gerard Carruthers of University of Glasgow, they show how Muir courted controversy in his early years.

The papers were assumed to be lost.

However the documents, more than 80 pages, have now been found in the Advocates’ archives and are to feature in a new book to be launched this week.

The papers deal with the early period of Muir's life, before his famous 1790s trial where he was sentenced to 14 years in Botany Bay.

Muir, from Glasgow, lived from 1765 to 1799, was one of the most famous political agitators and campaigners of his day, and was regarded after his death, in France, as a political martyr.

Professor Carruthers said: "I just think people had just been looking in the wrong place.

"They had perhaps been looking under Thomas Muir rather than looking under the Campbell papers or the Dreghorn papers.

"I think partly the reason why these papers were overlooked was because they didn't deal with the 1790s trial where Muir is sentenced to 14 years in Botany Bay.

"These papers dealt with an earlier period when he is involved in local kirk politics."

He added: "The real significance of these papers is they show that he was a well-kent face, and the same people who are sitting in judgement on him in Edinburgh in 1793 just a few years earlier were aware of Thomas Muir making trouble as a representative of his local church."

The papers detail a chapter in Muir's early life while representing his local church, when he challenged local land owners, contesting their right to choose a church minister.

A Glasgow University statement adds: "The Court of Session papers show how Thomas Muir upset powerful key members of Scotland's political and legal establishment, including figures who were later instrumental in having him banished to Botany Bay in his sedition trial of 1793."

Over eighty pages of this new material bring into focus Muir’s activity representing his local kirk congregation at Cadder in today’s East Dunbartonshire, in the period 1790-92.

They show the minutiae of Muir’s opposition to James Dunlop of Garnkirk, a local land owner who wished to control the appointment of a minister for the parish rather than allow the congregation to have a free hand in appointment.

Although the preferred candidate of the congregation represented by Muir eventually secured the appointment, what the Court of Session papers show is that Muir lost the case, contradicting the usual biographical account.

Angela Grahame, QC, Vice-Dean of the Faculty of Advocates, said: "The Advocates Library is a treasure trove of fascinating, historical documents.

"We are delighted that the vast amount of published information which we preserve has provided a telling contribution to this book and to a new insight into the man who holds such a prominent place in Scottish history and culture.”

After his trial for sedition in 1793, Muir was found guilty and banished to Botany Bay, Australia, for 14 years.

He escaped from Australia two years later and fled to France, calling on the French Government to “liberate Scotland” but he died two years later.

Professor Carruthers' book: Thomas Muir of Huntershill, Essays for the Twenty First Century is being launched at a special event at Kelvin Hall, tomorrow, December 15.