It was an unfortunate time to join the British Communist Party because by 1927 it was already exhibiting signs of political degeneration and slavishly sided with Joseph Stalin's struggle against Leon Trotsky. Slater very quickly sided with the revisionist Stalinist theory of building Socialism in One Country in opposition to Leon Trotsky's orthodox Marxist position of permanent revolution.
The CPGB slavishly followed the Soviet party's line. When anybody stepped outline such as in the case of Maurice Dobbs who wrote for a journal that had "Trotskyists" writing for it, he was forced into a humiliating retreat.
According to John McIlroy "by 1933 G.A.Hutt was denouncing accounts of the development of Marxism which failed to privilege Stalin by an invocation of Stalin's letter, declaring: 'There is no true Marxism today that is not Leninist. Lenin developed and extended the work of Marx and Engels and Lenin's unchallenged successor in the field of both theory and practice is Stalin'. A new orthodoxy, a new canon and new controls over party intellectuals were in place: in late 1933 the requirement that books written by CPGB members were to be submitted for approval by the party leaders was formalised". 
Any assessment of Slater's literary work should take into consideration his Stalinist politics. His craven adherence to Stalinism paved the way for him in the 1930s to become founder and then editor of the journal 'Left Review' in October 1934. Left Review from the beginning was an apologist for Stalinist crimes against the working class and became a house organ for attacks on Leon Trotsky.
As Brian Pearce writes "right from the very first number, Left Review revealed where its basic allegiance lay, with a poem by Louis Aragon glorifying the speed-up in a Soviet tractor-works. And in the number for February 1935 Tom Wintringham, one of the co-editors, launched a violent attack on Max Eastman's book Artists in Uniform, which had shaken illusions among some left-wing intellectuals about the position of literature and the writer in the Soviet Union. A characteristic jolly-them-along phrase in Wintringham's article ran: 'Not a few bureaucratic absurdities have happened at times during the Soviet Revolution. And as soon as the party has been able to be quite clear on what it is all about – they go.' (Wintringham was himself expelled from the Communist Party only a few years later, for keeping company with the daughter of an alleged Trotskyist.)
Pearce continues “In November 1937 the publisher Frederick Warburg revealed in a letter to the New Statesman that Left Review had refused an advertisement for The Case of Leon Trotsky, published by his firm. This book was the report of the examination of Trotsky, regarding the statements affecting him made in the trials, carried out by an independent commission of inquiry headed by John Dewey. The new liberalism of Left Review did not include giving a show to the other side. Editor Randall Swingler explained on behalf of the journal, in the next issue of the New Statesman, that "there is a line at which criticism ends and destructive attacks begin, and we regret that this line separates us both from Dr Goebbels and Leon Trotsky”. 
Slater, who died at a very early age of 54, stayed true to his Stalinist ideas. Despite being linked with the new Reasoner wing inside in the Communist Party, Slater agreed with every twist and turn of the British Communist party' s attack on Trotskyism. He backed the party's reformist "British Road to Socialism". When the Hungarian Revolution took place in 1956, Slater called it a counter-revolution. He died in 1956 still retaining his party membership.
Englishmen with Swords
As was said before any assessment of Slater'ss literary achievements should within the context of his politics. Englishmen with Swords is a piece of historical fiction which centres on the years 1647-1649, these years being the highpoint of the English Bourgeois revolution. Slater wrote the piece using material from the journal of a minor but significant real-life participant of the English Civil War Gilbert Mabbot.
As much as I can tell, the storyline remains faithful to actual events. The book should not be seen as a historical document but should be seen as a complement to academic historical research.
Slater does bring Mabbott to the attention of a wider audience. Too many figures such as Mabbott have been lost because revisionist historians reluctance to research figures such as Mabbott and others. Revisionists attempt to replace "history from below" genre with history from above has done much damage.
Mabbott (1622—c. 1670) was according to Graham Stevenson "the official licenser of the press from 1647 to 1649 and himself a pioneering journalist and publisher of newsbooks during the English Civil War period". He was significantly linked to radical groups such as the Levellers during his publication of the Moderate newsbook.
Describing his time with the Moderate Mabbott said: "I have laid down my former title of 'Moderate Intelligencer' and do go by another, 'The Moderate'". The Moderate espoused republican views. It fully supported the execution of the King and held views that were similar to the Levellers.
Mabbott'ss link to the Levellers has been questioned by Frances Henderson who said "Mabbott's reputation as a Leveller, which rests solely on his alleged editorship of the radical newsbook The Moderate, is open to question. It is possible that he contributed to early issues of this newsbook, but there is no evidence that he was responsible for editing it and nothing in his career or conduct to link him directly to the Levellers".
Henderson's view have in turn been challenged by Pattrick Ludolph "Gilbert Mabbott was a licenser of pamphlets and newsbooks from 1645 to 1649. He was also brother-in-law to Sir William Clarke and a client of John Rushworth. From 1647 to 1649, he was in the pay of the New Model Army, acting as their "agent" in London. As well, Mabbott has been accused of being the editor of the radical newsbook The Moderate, an accusation which I have come to believe".
Patrick's views on Slater's book is worth quoting "I have read it, but I could not tell you much more about its background than what is already on the dust jacket. It is from Gilbert Mabbott (which you know because you commented here, but I thought I would say for others out there) and makes use of several original documents from the Civil War. However, Slater chose Mabbott because he knew absolutely nothing about him.
He saw his name on a bunch of documents and decided to write from his viewpoint because Mabbott was a virtual nobody, a clean slate to write on. The irony is not lost on me. It has been a while since I looked at it; I seem to recall that Slater was a little confused about some things, but I do not remember what. Come to think of it, I probably should have done a post on this, but I read it before I started blogging".
To conclude, it is difficult to say how good this book is. As Chris Hopkins says "Lukacs in his The Historical Novel (1937; 1963) distinguishes between various periods when literary historicism has become merely a mannerism and periods when historical genres have made authentic engagements with history, as some of his section titles may briefly suggest: 'The Classical Form of the Historical Novel', 'The General Tendencies of Decadence and the Establishment of the Historical Novel as a Special Genre'. Lukacs, of course, as one of the most influential Marxist critics of the twentieth century sees the success of the historical novel at different period as not simply an aesthetic matter, but as one deeply determined by history itself" 
 The Establishment of Intellectual Orthodoxy and the Stalinization of British Communism 1928-1933 John McIlroy Past & Present, No. 192 (Aug., 2006), pp. 187-226
 Brian Pearce-Some Lessons from History:The Left Review, 1934–1938
(November 1959)From The Newsletter, 7 November 1959.Transcribed by Christian Hogsbjerg.
 Historicising the Historical Novel: Introduction-Chris Hopkins, Sheffield Hallam University