There I was, watching the sun go down from inside this vast, gorgeous film set of a restaurant in Stone Town, Zanzibar, but I couldn't escape the full absurdity of my position.
I was there ostensibly to tread the path trod by John Hanning Speke, who is celebrated for discovering the source of the Nile more than 150 years ago. Speke endured as much hardship as anyone can take in his quest for glory, to answer a geographical conundrum that perplexed not only the Victorians but the ancient Greeks, Romans and countless others.
Also read: The Nile: Why the river is a source of life and rivalry in Egypt
My biggest worry was how I was going to get a decent picture of Freddie Mercury’s birthplace – which happens to be up the road.
The excuse for my research, disturbed only by the vigorous crushing of ice by the bar staff and some agreeable Ghanaian jazz, was that I am distantly related to Speke and have always been tremulously conscious that my family has A Great Man among our antecedents.
So when time and the beneficence of British Airways allowed, I took the opportunity to visit some of the key places along his routes. What I did not want to do, in my squeamish, western-liberal way, was impose any European view of whether and how Speke ought to be remembered. I just wanted to know if he is remembered, and, for better or worse, how.
Speke was the model young Victorian gentleman – conventional, soldierly, the son of West Country gentry – and he had been chosen by the leader of the expedition, Richard Burton, partly because his outdoors-oriented skills would complement those of Burton, whose interests lay chiefly in ethnography, anthropology and language, particularly of Arab people.
The pair set off inland from Africa's east coast in June 1857, hoping to meet the beginnings of the Nile as it flowed north and ultimately into Egypt. Its end was clear enough, the Mediterranean, but as maps of the time show clearly, nobody knew where it began.
Their base at Zanzibar had been the beachside British consulate, but now, happily, it is the Livingstone Restaurant. That is where this impostor – under a fan – was contemplating Speke's extraordinary achievement in what at the time was one of the world's most menacing natural environments.
He has been called "the discoverer of the source of the Nile", but the term remains problematic. The idea of anything being "discovered" when local people had known about it all their lives is already absurd, but what is true is that Speke and Burton were the first white people to see much of the African Great Lakes region. Whatever their motives may have been, and whatever the extent of local help they purchased, that physical achievement in so inhospitable a terrain and climate is still remarkable.
A further corrective is that, while the journey was extremely perilous, Burton and Speke were not in entirely virgin territory. Arab traders – and before them Portuguese – had become familiar with much of their route, but a good deal of it was hostile.
They were not traders, and needed to start afresh to be allowed through tribal fiefdoms. Also, they had plenty of assistance, bringing about 120 porters and other staff with them, although this brought its own difficulties.
Three weeks after leaving the coast and heading southwest, following the path of the Ruvu River (where part of the rail line to Zambia now runs), the party, already beset by illness, mutiny and dissent, reached Zungomero. This major junction, where traders would halt and re-stock on their way to the slave and ivory markets on the coast was, in Burton's words, "a hotbed of pestilence".
I hoped to find someone with faint family memories of the explorers, but it was a futile search. It was hard enough finding Zungomero, which has ceased to exist as a town, and the plain on which it was situated now plays host to a handful of Tanzania's vast army of subsistence farmers. In a pale nod towards Speke's pioneering, I did manage to hack back some greenery to uncover an old road sign, but it was hardly heroic.
David Guthrie, owner of the magnificent Sable Mountain Lodge in the jungle on the northern edge of the Selous National Park, joined me in some amateur sleuthing, translating chunks of Burton's account of their journey into Swahili for the benefit of rapt villagers as we looked for signs at least of the German administration of the area in the 1880s beneath the copious vegetation. However, the German presence was all post-Speke.
Edward Rice, a chronicler of the Speke-Burton relationship, wrote of their departure from Zungomero: "Struggling under appalling conditions, two sick men, handicapped by insufficient resources, a shortage of porters and animal transport, lack of equipment, and a rebellious caravan, pushed ahead into an Africa that no European had ever seen and which even the long-experienced Arab traders approached with caution and fear."
I kept my copy of Burton’s book deep in my bag in Tabora, the next large town on the slave route and effectively the country’s crossroads, which provided so many of the porters who worked for Speke and Burton.
It was at Tabora – then known as Kazeh – that Burton's fondness for Arab culture and custom was most welcome. There the explorers were treated with impressive hospitality by local traders, who helped with their physical recovery from the rigours of their travels, and with general information about acquiring porters, food and so on. In his characteristically dismissive way, Burton wrote of the "futility of the local Africans", ruled at the time by the Fundikira family.
Burton, no loss to the diplomatic service, saw himself as a student of ethnicity and tribalism, and what to modern eyes looks like rank racism would to him have been merely what might be called ethnicism, a branch of science. Yet his gleeful sense of superiority in his purportedly encyclopaedic descriptions of local custom (Speke was also guilty of this, if less so) makes the 21st-century reader wince.
He wrote of the son of the king travelling as a porter towards the east coast when he heard news of his father's death in Tabora. The son turned round and headed home, inheriting "all his father's property and  widows" and building 300 houses for his slaves and dependents. But within months he fell ill, and it was assumed among locals that someone must have willed this on him.
Witch doctors used particularly gruesome methods to identify the culprits, many suspects dying in the process, according to Burton, who also noted in passing that “the Wanyamwezi will generally sell their criminals and captives; when want drives, they will part with their wives, their children, and even their parents”, bringing in replacement labour from cheaper parts of the country.
I was fortunate enough to meet Ifuma Fundikira, who was in his late 50s, and two of his brothers. Had Tanzania's post-colonial history taken a different path, they would still be royalty in the area. He lives the modest life of a farmer, but Ifuma's pride in his ancestry was obvious, and he showed me a family tree that goes back to 1727. Was he aware of the story that Burton tells of Fundikira's great-grandfather? He was dismissive. It was inconceivable that the king's son would have been working as a porter, he said. The story couldn't possibly have been true.
Did he have any family stories about Speke and Burton? He said they were both extremely ill when they arrived in Tabora. When the Fundikira family first met the explorers, he said, they were so exhausted that they each drank 12 cups of tea "with cloves, and milk". There were no other family memories of Speke, although they still hoped a mooted Wanyamwezi museum might come to fruition. The Fundikiras provided Speke, Burton and their caravan with medicine and accommodation, and sent them on their westward way again.
The pair's health was yet worse when they reached their westernmost destination, the shore of the vast, spectacular, shard-shaped Lake Tanganyika, which separates Tanzania from the Congo, and which Burton believed was the source of the Nile. The pair rested on the shores of the lake and tried to regain their health after close brushes with death, their spirits sagging after it became clear the lake could not be the Nile's source.
Knowing of their further brushes with disaster, my expectation of the lake was of a mosquito and crocodile-infested death trap, and life on the shore of the lake is assuredly tough, however beautiful the surroundings. But I was fortunate enough to be staying at an oasis of comfort, the sort of heavenly place that, in a just world, everyone would be able to visit at least once.
Nomad Greystoke lodge in the Mahale nature reserve is to the south of Ujiji, which was famously visited by not only Speke and Burton but also some years later by British explorer David Livingstone. Whereas further north there had been a shocking degree of deforestation, Greystoke Mahale was surrounded by the same dense greenery that the explorers would have seen – and some truly affecting chimpanzees, charmingly, wonderfully unconcerned by the intrusion of the only small handfuls of tourists allowed to visit.
The contrast with Speke and Burton's experience of Tanganyika's wildlife could barely have been greater. Speke, already exhausted and partially blind, was afflicted by a beetle that crawled into his ear. His only hope was to get it out with a knife, which didn't work. The insect splintered, the wound went agonisingly septic and he went deaf in that ear. I worried, as I sprawled shamelessly in my magnificent beachside four-poster bed, about where I had left the cotton buds.
Having established, after all, that Lake Tanganyika could not be the source of the Nile, Burton and Speke – both ill and, as the great historian Jan Morris put it, bickering like a husband and wife – decided to head east again towards Zanzibar and back to England. When they reached Tabora, Burton insisted on pausing to rest and spent time with his Arab friends. But Speke was not done. They had heard talk from local people of another big lake located somewhere to the north of Tabora, and the great Nile must start somewhere.
This was the key moment that puts Speke into the category of great explorers. He had the drive, the nous to listen and the durability to keep going on his quest. So he and a handful of porters set off on a 25-day march, not knowing what they might find and, on August 3, 1858, he made his way over a hill and saw an enormous inland sea. Locals said no one knew where it ended. We now know it is the size of the Republic of Ireland. This, Speke declared, must be the source.
Although he could not prove it, and his argument was not accepted until several years later, Speke thus became associated with the belief that Lake Victoria (as he named it) was the source of the Nile. Plenty of people still dispute this, pointing out the vastness of the River Kagera and others that flow into the lake, making it not so much the source but a basin, a receptacle for the waters that flow down from the mountains to the west.
Speke returned south to Tabora, where Burton was never likely to share the conviction of his "companion", as he distantly referred to Speke, about the supposed discovery. Speke hadn't seen the Nile flow out of the north side of the lake, which he believed it did.
In Uganda, there are streets and schools named after Speke. If he was ever bracketed as one of the exploitative colonials, he had been forgiven. So when I was in Mwanza, the fast-growing Tanzanian town where Speke had his first glimpse of the vast lake, I was interested to find out how much resonance his name still had among its population. Older people I spoke to knew his name, but I had a sense that the Nyerere government of the 1960s had written him out of the country's history.
My guidebook said there was a monument to him on the main roundabout in central Mwanza, but initially I couldn't find it. Eventually I went into the tourist office which, fortunately, overlooked the city's hub. I explained that I was looking for the Speke monument and asked whether they could point to it out of the window. I was told, with some certainty, that there was no such thing, and what was his name again? It didn't seem to be going well.
I went outside again and found two gardeners who were tending the grass on the roundabout. If anyone knew if the monument was nearby, surely they would. Nope. Eventually, I found a barely legible plaque, proclaiming that "one mile from here", Speke became the first European to see the lake.
I had to go back to the nice woman in the tourist office to point out that I was not completely deluded. She shut up the office and insisted on coming to have a look. "What was the name again?" she asked. I told her. At last the light seemed to dawn. "Ah, I see," she said.
She inspected the plaque, and as we walked back to her office, she said, I thought very sincerely: "This is really interesting. I must tell my bosses in the regional office. I don't think they know anything about this. We must have it displayed better."
Would that be a good thing? Despite myself, I was rather pleased.