Nairobi, Kenya - How do you find your way around a town you knew 40 years ago?

Not easy under any circumstances, and even in a place that made such a lasting impression. In practice, the challenge quickly became almost impossible.

The town in question, Nairobi, 1975 population circa 500,000, has become a huge city, 2017 population circa 4.5 million.

As I drove, well, crawled really, given the suffocating traffic, around Kenya's capital this week, I often felt disoriented. I found myself saying, again and again, 'I don't remember this road, or that tower block, or that hotel, or that flyover'.

The truth, of course, was that I didn't remember that road, or that tower block, and so much else, because they had not been there. There was nothing to remember.

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Intellectually, I had been prepared for this obvious truth. The demographic facts speak for themselves. Population growth of 800 percent makes for some dramatic changes. And yet, emotionally, it was still a shock.

Not only was so much new, so much old had disappeared. The city had not only expanded outwards and upwards; it had devoured much of its earlier versions of itself.

I strained to look for familiar roads, lined by trees and bungalows. In many places, they'd been wiped off the face of the earth.

Booming construction

Only Nairobi's topography, its hills and valleys, its dips and troughs, gave me clues as to where I was and tormented me with hazy memories. I wanted to reach out, to capture the whole picture of how things were. But it's gone, forever.

I told a Kenyan of my generation of my difficulties. He laughed, and said, "Don't worry, you're not the only one. I've never left, and even I get lost these days. The building never stops".

The pace of Nairobi's transformation is accelerating. The economic improvement of the past 15 years has led to a boom in property prices and construction.

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The new skyscrapers, giant apartment blocks and malls have transformed Nairobi, but there's much more to come.

A friend sent me a link to an article, 'List of 13 Skyscrapers Under Construction That Will Define Nairobi's Skyline'. They include plans for the tallest building in Africa, currently a giant hole in the ground that will soon be 67 stories of concrete and steel.

Marooned between these new towers are a handful of the old colonial-era bungalows. Sitting on land worth millions of dollars, they are doomed.

I could blame the corruption and greed that makes it so easy for well-connected land-grabbers to break rules and cut corners. But in truth, in any society, the economic logic would be overwhelmingly on the developer's side.

Resisting change

I sat in a small Nairobi garden, talking to a Kenyan who has closely followed these changes and tried to resist the worst of them.

Irungu Houghton is a fighter, and an eternal optimist, undeterred by death threats. "We've mobilised our neighbourhood, and we've had small victories," he said.

Irungu told me a nearby hotel had agreed to remove the ugly spiked fence from around its perimeter and replace it with plants.

He's campaigning for decent public toilets on a main road to serve street traders and pedestrians whose poverty effectively excludes them from hotels and malls.

He and his friends have planted thousands of trees in the surrounding streets. And yet, Irungu's garden told its own story. It's a tiny patch of greenery, now overshadowed by the giant apartment block being built by a Chinese company next door.

We found ourselves talking over the din of construction.

"We've had two years of dust and noise," he said.

"At one point, they were building through the night, until I managed to get some of them arrested," Irungu added with a weary smile.

He went inside to fetch a pole, to remove a white plastic bag covered in Chinese writing that had floated down from next door and snagged on his roof gutter.

When the block is finished, he'll have some 250 new neighbours, living on land formerly occupied by a single family, their cars clogging up the dusty lane outside.

'My Nairobi'

Nairobi has never stopped growing and has always been in flux, ever since the British put up a little settlement on the then vast Athi plains in 1899.

'My Nairobi' of the 1970s, would no doubt have been a disorientating place to any visitor who'd last known the town in the 1930s.

Like those other British colonial creations in the high plateaux of the African interior, Johannesburg and Harare, Nairobi has gone from zero to many millions in a bewilderingly short space of time.

I struggle to think of any historical parallels. London, the world's largest city in the Victorian age, grew by 600 percent during the entire 19th century, but it was already a great city in 1800, with some one million inhabitants.

I can't deny, and the reader will no doubt have already detected a certain sadness. I miss the Nairobi that I grew up in.

A place where houses were not surrounded by gates and guards, where streets were not jammed with traffic, the roadside bougainvillaea not coated in dust.

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Where the evening calls of the doves and the kites overhead, so evocative after all these years, were not all but drowned out by the metallic whines and bangs of construction and roars of engines.

I don't want to romanticise the past, and I'd be a fool to deny how privileged my life was in 1970s Kenya. We had a car and a house with a spacious garden, and went on exciting holidays, whereas then, just as now, the majority of Kenyans were fighting an exhausting daily battle to escape poverty.

I can still remember the embarrassment when we emerged from a downtown cinema in the evening and were quickly surrounded by children in rags, begging for a few coins.

I recall, also, the fascination with which I peered from the window of our blue Ford Cortina as we drove past Mathare and Kibera, the vast slums on the edge of the city, or watched the elderly Kikuyu women bent double under bags of firewood as they trudged home.

I was sorry, but of course not surprised, to see that a new generation of hungry children was begging and sniffing glue in downtown Nairobi today and that the shacks and muddy lanes of Mathare and Kibera have spread relentlessly over the decades. At least in its grotesque inequalities, Kenya has been consistent.

Privatisation

"What we need to reclaim are our shared public spaces", says Irungu. "The wealthy in our society have privatised everything - their security, their children's education, their shopping spaces, their supplies of electricity and water".

In the 1970s, I went to a public, Nairobi City Council primary school. As a white boy, I was in a distinct minority, but I was far from exceptional.

My classmates included children from some of black Kenyan society's wealthiest families, but also many children who could barely afford the school uniform.

Other goods and services were still shared in the public realm. Nobody owned an electricity generator, everybody drank water from the taps.

We all travelled on the same train (albeit in different classes of carriage) down to Mombasa at Christmas.

We shopped downtown, not in privately-owned malls in the wealthy suburbs. In fact, there were no malls.

There were no 'gated communities' either, and although the police were far from perfect, there were no uniformed private security companies to guard the elite and expatriates.

Diminishing race tensions

It seems more than wistful nostalgia to bemoan these changes, and the fracturing of society they represent.

And yet, as I talked to more and more people in Nairobi this week, I found many changes worth celebrating.

Even as a schoolboy, I sensed that 1970s Kenya could be an intellectually and socially stifling place. Race relations were often overshadowed by the anger, fear and jealousy that had built up during the colonial years. British rule, with its fundamentally racist logic, had been replaced by a repressive one-party state.

No newspaper dared to criticise President Jomo Kenyatta, and some of the handful of politicians that had the courage to do so were jailed, or even assassinated under mysterious circumstances.

'The old man', Mzee in Swahili, was an overwhelming presence, his advancing years a taboo subject for public discussion. "So when he died [in 1978]," a colleague recalled, "people were afraid to mention it for some time, in case he came back to life and asked which ones had been talking of his mortality".

Compare those days with the present. Race tensions still exist but seem much diminished.

Public debate, in the newspapers, on the radio and social media, is raucous, humorous and uninhibited.

The sheer numbers of Kenyans who have worked their way through the education system over the decades have built a lively and dynamic society that exudes energy and optimism.

Last day in Nairobi

On my last day in Nairobi, I ended up having tea with my old neighbours, the Patels (not their real name).

I'd heard from a mutual friend that they still lived next door to the house we'd lived in, and I was keen, although also apprehensive, to see what the neighbourhood looked like.

I stopped first at our local shopping centre, Hurlingham, which had survived, but, hemmed in by surrounding buildings and relentless traffic, had clearly seen better days.

The money is in the malls these days, and several of the Hurlingham shops were boarded up or deserted. But, to my surprise, Puffins was still there. Puffins!

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To a school boy, this modest shop had been an exciting emporium, a place to buy children's books, magazines, postcards of wild animals, and Matchbox toy cars.

Dimly lit and with shelves stacked chaotically high, I was gratified to find Puffins sells very similar merchandise today, with apparently little concession to the digital age.

"But I don't know how much longer", the owner told me. "A developer says he has permission to build here, and that's why others have already sold up".

A couple of doors up, Sussex Bakeries, from where alluring smells of fresh bread and doughnuts once drifted out across the carpark, was no more. In its place stood a noodle restaurant, Chop Stix. It seemed a suitable metaphor for the passing of the baton in Africa from British to Chinese influence.

'It's a peaceful country'

I drove from Hurlingham, turned left past the Chinese embassy, a couple more turns, up a hill and over a roundabout.

The entrance to our old street, now blocked by a black metal gate, was unrecognisable, and I went right past it before stopping to retrace my route. "Please, I lived here 40 years ago, and I'd like to take a very quick look inside".

The uniformed guard was suspicious, but slowly opened the gate to reveal the sloping little street which is branded in my memory.

To my surprise, it seemed remarkably unchanged. A fortified island of green and calm, surrounded by the frenzy of the new Nairobi.

Another metal gate, also a new addition, blocked the driveway to our own house. Peering through, the garden looked unkempt and the house unoccupied.

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So I went next door and rang the Patels' doorbell. I remembered them as a stylish and sophisticated couple, in their 30s.

When I was a small boy, I played with their sons, and they'd take me to Indian weddings in Parklands, events memorable for delicious food served on large metal trays, served up to hundreds of guests sitting on benches in large halls.

Now, 40 years later, I sat in the Patels' living room and drank tea. We asked after relatives and friends, in an atmosphere of mutual astonishment and excitement.

Kenya's ethnic Indian population have at times had an ambivalent, even precarious, position in their country's history, a relatively prosperous but resented minority.

Many of the Patels' relatives now live in the United States and the United Kingdom.

We had not discussed politics but Mr and Mrs Patel, both now approaching 80, made it clear they are not going anywhere.

Mr Patel flung his arms up and gestured to the sinking sun on the lawn outside. Two glossy ibises, large birds with shiny plumage, picked their way over the grass. He said, "It's a peaceful country, we have no regrets".