Nairobi's Lady of the lamp

Robin Mwangi never saw them coming. Out of the darkness, eight figures emerged. One held a gun to his head while the others took what they wanted. Mr Mwangi's phone and money were stolen and his stall, which sells mobile phone credit and fresh meat, was ransacked.

The gang sauntered off into the night of the Korogocho slum on the outskirts of Nairobi. Within seconds, their shapes had disappeared into the darkness, leaving Mr Mwangi with no clue as to who had attacked him.

A streetlight stands directly opposite Mr Mwangi's stall but on the rare occasions it works, it emits only a weak glow. From across the street - a dusty, rubbish-strewn, single lane lined with stalls and shacks - it is impossible to recognise someone standing underneath the light.

Nairobi's slums have been without proper light for as long as they have been slums. Women cannot walk at night without risking attack by rapists. Stalls cannot open late for fear of being robbed - even when they do there are few customers willing to venture out. Children who do not have light in their own homes - often nothing more than a tin shack with a bed and a stove - cannot find the light to do their homework.

Roughly 70 per cent of Nairobi's three million population live in slums like Korogocho. At night, paraffin lamps and illegal connections to the city's main power supply provide dots of light across the two square kilometres that is home to more than 200,000 people.

That may be about to change. Outside Korogocho community health clinic a vast red and white striped pole towers above the slum. At its peak stand eight beam-lights ready to blast light across Korogocho. Four more are planned. They will be placed at strategic points across the slum, lighting up Korogocho's darkened corners. The pole has been put up by Adopt-a-Light, a Kenyan lighting company that has revolutionised street- lighting across Nairobi. In the five years that Adopt-a-Light has been installing streetlights in Kenya's capital, the city has been transformed. Highways and parks that were once covered in darkness are now bathed in light. There are fewer traffic accidents and less crime.

By placing advertising hoardings on every light pole, Adopt-a-Light has managed to turn a public service that the city council was failing to provide into a business opportunity that has made streetlighting profitable.

Esther Passaris, the businesswoman who set up the company, has become one of Kenya's most famous women. Now she has grand plans to expand Adopt-a-Light deep into the slums and has launched an anti-poverty foundation that aims to get one million Kenyans to donate money to slum upgrading.

"We will need more than advertising to light up the slums," she said. "When I go into the slums if I just light them up am I really helping them?" But just as Ms Passaris has begun to extend her project into Nairobi's slums a bitter row has broken out over the terms of Adopt-a-Light's contract. Critics have accused her of holding a monopoly, the council has taken her to court and the anti-corruption agency has begun an investigation.

When the contract was signed in 2002 it had a clause enabling it to be automatically renewed every five years, providing Adopt-a-Light had stuck to the terms of the agreement. The city council now claims Ms Passaris has broken those terms by installing lights - and claiming revenue - on streets the contract did not cover. The contract has been annulled and the council has begun pulling down streetlights, calling for bids from other companies. Both sides are preparing for a lengthy legal battle.

When the contract was signed, the council was only too happy to give Ms Passaris responsibility for street-lighting, granting Adopt-a-Light the freedom to set advertising rates and keep any profit. "They had no light bulbs, no equipment, no money," Ms Passaris said. "All the light poles were beyond repair. They didn't have the technical know-how. I gave them a proposal. They were so desperate they took it.

"I had to sell my house to fund the company. When the council started seeing they could make money their attitude changed. They forgot I was the one who put the work in."

The row has been rumbling since February when Nairobi's deputy mayor claimed Adopt-a-Light had secured the contract "irregularly". Some of the Adopt-a-Light's employees have been arrested while replacing old street lights and Ms Passaris has been taken to court more than a dozen times as the row has escalated.

Few government services can be found in Korogocho. The schools are full to bursting and lack teachers and textbooks. There are no paved roads, few public latrines, and the rubbish is never collected.

Instead, the rubbish is dumped in Korogocho. You can smell Dandora dump before you see it. Maribou storks circle above while young children pick their way through Nairobi's garbage searching for food and items to sell. Kenya Airways dumps its rubbish here - finding a discarded bag of uneaten airline meals can be like striking gold. Enough passengers fail to use their small carton of butter or jam - they can be sold on Korogocho's streets for a couple of shillings.

But when the sun goes down at around 6.30 in the evening, the bustle of Korogocho's main streets and alleyways quickly disappears. Many still venture out but the fear of crime is strong.

A solitary streetlight opposite Mr Mwangi's stall in Korogocho may not lead him on the road to riches but it would make an enormous difference to his life. "I will be able to open later, make more money and look after my family," he said. "And maybe I won't get robbed."