I’ve been thinking about Roger Casement a lot recently. The complexity of human personality is no more evident than in his colourful life, and the exercise of piecing it all together, nearly 90 years after his death, is fascinating and compelling. Like all posthumous biography, it can only be educated speculation, and, as with all controversial figures, biographers have their own agendas and identifications and points to get across. But if, by some miracle, he were around today to tell us what his life was really like, I’m not so sure whether he’d know how to speak his truth. I suspect the reason there is so much animosity around his legacy, so much suspicion and vitriol, is that he was a fantasist, and his inner psychological split, between sexual predation and celibate piety, was worked out in his diaries, in Black and White.

The inconsistencies in content and style between the two – the fluent, engaging white and the stuttering, innuendo-laden, lascivious black, have led some people to believe that the latter are British forgeries, which suits a particular mystic Irish nationalist sensibility down to the ground – the devils are external, and both sins of perversion and dastardly deception are laid at the door of the perfidious Brit. Once the British confess to the forgery, then we can get back to the business of celebrating his martyred whiter-than-white life with his reputation intact.

But someone who has no such Celtic axe to grind, whose passion is Latin American history, Angus Mitchell, in his celebratory reproduction of Casement’s “White” 1910 Amazon journal, writes in the preface that he simply does not recognise the writer’s voice in the Black Diaries. Convinced that they were not written by the Casement he had come to know so intimately, he says: “Whoever wrote the diaries had a desire to portray Casement and homosexuality as a sickness, perversion and crime for which a person should suffer guilt, repression, fantasy, hatred and, most of all, alienation and loneliness. These are not the confessions of a Jean Genet or Tennessee Williams, W.H. Auden or Oscar Moore. Rather than sympathising with the struggle of the homosexual conscience, they are clearly homophobic documents.”

That statement alone suggests to me that there is only one person who could have written them: Casement himself. Homosexuality and self-reflective creative talent are not synonymous, and it is disingenuously “liberal” to suggest it. The clumsy furtive pornographic aides-memoire that he churned out in the Black Diaries were meant to make sense only to himself, as wank-fodder, whereas his White Diaries were his job – he was a report writer, a civil servant, writing and recording daily, his diaries intended for publication, with no pretensions to creativity.

Whatever evidence there is to speak of a gay consciousness or sensibility in the 21st century, there is none to suggest any such beast at the dawn of the twentieth, for Freud was only just beginning then to lift the lid on sexuality, and Wilde’s ignominy and death in 1900 cannot have done anything but to dismay anyone with a similar predilection. The word “homosexual” itself only began to gain currency in English after Wilde died. Back then, things were black and white – the concept of the rainbow, the symbol for human diversity and inclusivity that can be found hanging as a flag somewhere in every gay bar nowadays, would have been alien to Casement.

The “struggle of the homosexual conscience” is not a generic thing, it is always individual, and has more in common with any man’s struggle with his desire nature than anything specifically to do with finding men or women horny. The fascinating thing about Casement is not that he had struggles with his sexuality, but that he wrote about them, in quite a dull-witted way. He was no Wilde. Why should he have been? There is no doubt that many public figures of that era had seedy private lives, but none of them was daft enough to record them.

Before Ireland, the heart of darkness of the Congolese and Amazonian jungles – this is where Casement was drawn, as soon as he could leave home, spending 20 years in Africa. His role as conscience for the western world, with high-minded aspirations for humanity, may have been spurred by his own struggle against what he perceived to be his own, primitive, base nature. In other words, the very split that he tried to come to terms with, between his ideals and his desires, might very well have been the engine for his extraordinary missionary zeal, that led to such wonderful improvements in the lot of the Congolese and Amazonian natives, suffering at the hands of Europeans.

Owen Dudley Edwards has puzzled over how such a fine humanitarian could also be sexually predatory, holding views of other people that are sexually exploitative. If one can hold that paradox to be true, then we are on the way to grasping the complexity of Casement, and indeed of masculinity itself. If he were alive today, he might be a public figure, but he’d have a Gaydar profile, and he’d be wanking over the profiles with the biggest cocks he could find on the internet. Would he have had the balls to actually meet men for sex? Or would it all be cyberchat, staccato thrusts into the dark corners of his psyche? And if we were to find his hard drive 90 years from now, would we know, reading it, if he actually had sex with men or not?

Would it matter?