Before I made my Nile trip in 1996, I’d read Speke and the Discovery of the Source of the Nile, Alexander Maitland’s gripping 1971 official biography of Speke, which had made me want to meet Maitland and discuss Speke’s source-of-the-Nile claim and its legacy. When I finally had the chance to do so at length last summer, Maitland told me that, “In the 1960s, Speke’s claim to discovering the source of the Nile was still accepted without question. It never occurred to me at that time that the hydrography of the White Nile [a tributary of the Nile proper] and its sources needed to be re-investigated.”

At approximately 6,700 kilometres, the Nile is the longest river in the world, but before 1858 the great geographical question wasn’t “How long is it?” but “Where does all its water come from?” In the course of centuries, Roman legionaries, Portuguese Jesuits, adventurous Scots and erudite Frenchmen all tried to solve this riddle. Herodotus quoted a story that the Nile rose from two great equatorial lakes that in turn were fed by two snowcapped mountains. Thus, following the European discovery of two snow-capped mountains — Mount Kilimanjaro in 1848 and Mount Kenya in 1849 — the Royal Geographical Society chose Burton and Speke to lead an expedition to find the Nile’s source.

Their journey is the stuff of Victorian-era exploration legend — a caravan of about 20 porters and an escort of local soldiers, plus sickness, desertion, arguments and seemingly petty impositions by chiefs — but it did result in Speke becoming the first European to reach Lake Victoria and making his claim, which many of his peers disputed, Burton ridiculed and the Royal Geographical Society eventually accepted.

But nearly 50 years after his biography of Speke was published, Maitland wonders whether the explorer had private doubts about his own claim. “Today, technology and satellite photography enable us to view the region in great detail. Obviously, these weren’t available to Speke in the 1860s, nor to me in 1965, when I began my research for his biography. Only some years later was my attention drawn to an intriguing note, one of 78 handwritten corrections in Speke’s own copy of his book What Led to the Discovery of the Source of the Nile.

“It revealed that he had wondered about the significance of the Kagera River. Perhaps with all the knowledge available to me today, I should rewrite Speke’s biography — it would be a fascinating experience.”

I urge Maitland to do this. It would allow him to present a complete biography of one of the Victorian era’s greatest explorers and explain to a whole new generation of geographers and historians the true mystery of the source of the Nile.