MICHAEL Fry's latest instalment of the alleged History of Scotland is really too much (May 7). The rubbishing of Thomas Muir and the whole pantheon of Scottish Radical history is nothing new but at least in the past those engaged in this dubious occupation had some pretensions to deal in facts, however much they might distort them.

Fry's description of the conditions in which Thomas Muir's body was found by the local authorities at Chantilly is worthy of the Booker Prize. The presence of a child of 12 at the deathbed and the involvement of the postman and the Mayor are verified by Muir's death certificate. All of the other details given by Fry are the entirely fictitious product of his imagination.

One of the most significant aspects of the discovery of Muir's body was the complete absence of any kind of documentation. There were no ''piles of papers: books, journals, pamphlets, letters,'' no piles of ''empty bottles,'' no ''reek of stale alcohol,'' as Fry claims. No Bible presented to him by his grieving parents from which to learn his name: Muir had disposed of that as a gift en route to Botany Bay.

His very name but not his identity was only known because someone remembered delivering him a newspaper so marked.

If Fry were as conversant with the evidence as he pretends he would know that Muir was still conducting highly sensitive negotiations with the French Government and fearing the presence of Pitt's agents had requested permission to leave Paris to go ''somewhere less conspicuous'' in order to protect his security.

There can only be two explanations for the total lack of papers at the death scene and that is that Muir was right and his room had been ransacked and all evidence of his identity removed, either by Pitt's agents or more likely Talleyrand's and Napoleon's officials, thereby protecting their own strategic intentions. That his death was officially announced in Paris would be entirely in keeping with the latter scenario.

Fry's account of Muir's role in the foundation of the Friends of the People is similarly inaccurate. Far from being a local leader in Glasgow he was from the very outset one of the chief promoters of the movement at a national level, and it was he who first proposed the calling of a National Convention.

Muir went to France in 1792 bearing messages from Lauderdale, Sheridan, and other leading Whigs to the leaders of the Girondists in the vain hope of preventing the execution of the King. The Whigs were certain that Louis's death would provide Pitt with an excuse for a declaration of war and while their faces were known and their movements watched Muir was unknown outside of Scotland.

Michael Fry's description of the United Irishmen of Belfast as a subversive movement in 1792 is shows an inability to separate fact from propaganda. Muir, along with Rowan and Drennen, were at that time reformers. That they subsequently become revolutionaries was due to the belligerent intolerance of political bigots like Fry's idols, Henry and Robert Dundas.

Muir was, like Lord Daer, an outspoken nationalist and a republican. His involvement in student politics which Fry condemns without explaining was in support of Professor John Anderson in one of his many attempts to clean up the sleaze at Glasgow University. The frustration of this effort led to the establishment of the Andersonian Institution and ultimately to Strathclyde University.

Muir was a cultural as well as a political nationalist and took an active role in Lord Buchan's Society of Antiquaries of which he was for a time Curator before he and Buchan himself were ousted by its Tory-Unionist majority.

Fry also repeats Henry Meikle's completely unfounded smear that Muir was isolated in his last days because of personality defects. The quarrel with Wolfe Tone is drummed up as evidence of this, whereas the reason for Tone's attack on Muir was precisely because he feared Muir's influence with the Government and his support for the rival mission of James Napper Tandy.

Muir had known Tandy since 1792. Tone was by contrast a complete and, by his own account, a belligerent stranger.

Instead of pathetically crawling away to a small town, slobbering his food, and drowning his sorrows over his disfigurement in a torrent of booze, as Fry would have us believe, all the evidence supports the contention that Muir was engaged in meaningful negotiations with the Directory until shortly before his untimely death.

Had his mission in conjunction with the efforts of the United Scotsmen succeeded we might have been spared the atrocities of the Clearances and Scotland might now be celebrating the bicentenary of its independent democratic republic.

Perhaps his autobiography, written in Paris in 1798 and last seen in London in the 1820s, may yet surface to finally give the lie to the scabrous fictions of his detractors.

Michael Donnelly,

343 West Princes Street, Glasgow.

May 7.