Fifty-five years after his death John Buchan is a puzzle. His books remain popular, especially those he called his “shockers” - The Thirty-Nine Steps and others featuring Richard Hannay which have been turned into films and television series.

But by no stretch of the imagination do these place him among the century’s best writers. From his parallel career in public service, he is the only Governor-General of Canada remembered in this country. Yet what did he do across the Atlantic that was out of the ordinary, and why despite his reputation did he previously fail to make his mark as an MP?

Was he simply a Scotsman on the make, a son of the manse who made it from Glasgow University to Oxford and then to the heart of the English Establishment? Or did he remain permanently an outsider knocking on the door? Did he spread his talents too thinly, starting as a writer to earn money as an undergraduate, and thereafter never deciding finally whether he wanted to cement his reputation in that field or as a politician?

Andrew Lownie, Buchan’s first biographer for 30 years, has devised the “Presbyterian Cavalier” tag for his title to suggest an enigma. The problem that Lownie has had despite access to more personal papers than were available to Janet Adam Smith, who wrote the only other full study (from the standpoint that her father had worked with Buchan) is that the Presbyterian side made Buchan reluctant to describe his own feelings and relationships.

He was ready to publicise his political views, especially a belief in the virtue of Empire that put him alongside the imperialist Liberals as much as the Conservatives with whom he laterly threw in his lot. He wrote about his ambitions and revealed his disappointments - from failure to be elected to All Souls at Oxford to rebuffs in seeking Cabinet office under the national Government. But behind the image of the man of honour and action, the countryman and clubman, the real Buchan stays hidden, as Lownie ruefully acknowledges. It is as if the writer is as one dimensional as his own heroes, Hannay, Sir Edward Leithen and other members of the Thursday Club. What did they think and feel and do when there was no spycatching wheeze on the go?

To outsiders Buchan was admirable and likeable. As Lord Tweedsmuir in his last years, the Canadians warmed to him, perhaps because like them he did not wear his heart on his sleeve. The grief at his early death in 1940 was widespread and genuine. But Lownie is able to point to difficult relationships at home. Buchan’s own father, an other-worldy minister, was remote from the family. His mother, who almost outlived him, was the strong influence on his life, a stern Calvinist who disapproved of his immersion in the Anglican Establishment. All of Buchan’s own children had problems in their teens and twenties. A worsening gastric ulcer made him bad-tempered, and his youngest son complained: “He is so cantankerous and one notices his filthy eating and his eternal boasting more than ever now.”

Lownie, an admirer of his subject, excuses Buchan from sins worse than inelegant table manners. The alleged anti-semitism which undermined his reputation is explained on the grounds that a writer who makes his characters sneer at Jews is not thereby endorsing their views, and that anyway anti-semitic jibes, like those at “Kaffirs” (as Buchan called them) where commonplace in his time. The exculpation is nevertheless forced, the link between Jewishness and financial malpractice is too frequent in Buchan’s books to be entirely fortuitous.

Yet, in another aspect of the paradox in the man, he differed from many Conservative MPs of the thirties in speaking strongly against fascism, and the Nazis denounced his pro-Jewish activities. He was also ready to adopt causes unpopular in the upper-class circles where he aspired to move (sometimes in the company of that other Scots arriviste, Ramsay MacDonald). For example, he protested against the banning of a lesbian novel by Radclyffe Hall.

He gained entry to the Establishment because he was selected by Lord Milner to help in the rebuilding of South Africa after the Boer War. He was rebuffed by the same Establishment when he embarrassingly pleaded for an honour for his war work. Only a Presbyterian - not a Cavalier - could fail to recognise the hypocrisy in that when set beside his grief for able friends whose only honour had been death in battle. Relying on his writing for his income, he made a mark with adventure stories rather than with his best novels such as Witch Wood and the later Sick Heart River, and the biographies of Montrose and Cromwell, immensely more complex men than his fictional creations.

Andrew Lownie, a member of the Buchan Society, is interested in the man more than the books. He tells his story concisely and pacily, but for a graduate of Edinburgh University and former Tory candidate in Scotland he makes a horrid number of mistakes with Scottish names. He appears more assured when his hero mixes in high places.