It all started when a cardboard wallet bearing Manchester University's name and crest was tossed into one of the dustbins in the middle-class neighbourhood which borders Matharé, Nairobi's oldest slum district.
The residents of the slums lurk amid those bins for the scraps discarded after meals and among them that day was Sammy Gitau, former slum child, thief, lavatory cleaner and drug addict, who, as a typical football-mad Kenyan, was attracted by the word "Manchester". He discovered prospectus leaflets inside the wallet - and references to his own country on a page about the university's "international development project management" (IDPM) course. With just two years of formal education, he dismissed all thoughts that he could make the course, but kept the wallet as what he now describes as "an inspiration, a fantasy of how things might be if I could ever reach that place".
In what must constitute one of Africa's more remarkable stories of redemption, Mr Gitau finally made it to Manchester this week to take up a place on the 15-month IDPM masters course which will help him to rejuvenate the Nairobi slums, whose deprivation became known to millions through last year's Fernando Meirelles film, The Constant Gardener. The last obstacle in Mr Gitau's journey was Britain's immigration service, which refused him a visa last year, saying his lack of education indicated he was not a serious candidate. Seven months later an immigration judge overthrew the decision, describing it as "thoroughly unsatisfactory and insupportable" and a visa was granted.
Mr Gitau was born into the poverty of Matharé, where an estimated 300,000 people are crammed into tin-roofed shacks alongside fetid open sewers. In the rainy season, the earth trenches sometimes overflow and flood the houses.
Mr Gitau's life descended into chaos when his father, who brewed illicit alcohol, was killed in a hammer attack. Aged just 13, Mr Gitau became the family's breadwinner. He embarked on thieving trips in Nairobi and was three times caught and beaten by angry mobs. He moved into selling drugs but in 1997 overdosed on cocaine and fell into a coma. He recalls hearing hospital staff say he would die, an experience he claims changed his life. "When you are dying you make a deal with God," he said. "You say, 'Just get me out of here and will do anything. I will go back and stop children going through the same kind of life a me."
It was the beginning of an extraordinary journey. Drawing on his experiences, he began easing young men away from drugs and glue-sniffing and established a community resource centre for Mataré, to lobby for fresh water and an electricity supply.
He came to the attention of the wife of the EU's head of delegation in Nairobi, Gary Quinn, and one of Quinn's staff, Alex Walford, helped him get cargo containers donated to convert into classrooms from which Mr Gitau and volunteer helpers teach subjects such as carpentry, tailoring, computer skills and baking.
Mr Walford was asking Mr Gitau about his own aspirations when the Manchester prospectus came up in conversation. "I'd moved it to a shelf in one of the containers, where I was living, but couldn't find it," he recalled. "I did remember the 'IDPM' though. Alex found the details on the internet."
Manchester now has as much to learn as Mr Gitau about the development of his training projects: run on less than $100 a month, they are seen as a model for effective grassroots aid. Mr Gitau's outreach work, which three assistants will continue in his absence, also helps more than 20,000 people with programmes ranging from drugs awareness to sprucing up the streets.
"I am confident many mutual learning opportunities will be on offer for this self-made, unassuming young man and all concerned with him," said his university programme director, Dr Pete Mann.