Trouble started earlier on March 30, 1950, when the East Africa Trade Organisation Congress started mobilising people to boycott the celebrations of Nairobi's charter after it became a city. Before the strike, an underground organisation, Anake A 40 ( young men of 40) had carved large swaths of the city into a fiefdom where police dreaded going and were extorting protection fees.
The Nairobi Municipal Tenants Association was agitating against high rents, the dilapidated state of accommodation, the chronic shortage of latrines, standpipes, and the absence of storm drainage for which it demanded 'immediate improvements.' The real drivers of the strike were the taxi operators angry with the government which was demanding that one had to know how to read and write in English before getting a licence. Petty traders too lived in daily terror of city authorities who were determined to keep them out.
When the government closed the trade union offices in Kiburi House in Nairobi and arrested the leaders, this sparked a strike that started off as a bonfire at Kaloleni Valley, which became like a watch power for the strikers. Since most of the Africans were allowed to live in crowded quarters in Pumwani, Kariokor and Kaloleni, these became the natural bedrock of the resistance.
David Hyde writes in Nairobi General Strike [1950]: From Protest to Insurgency, how a fire was lit in the Kaloleni Valley, an area between Shauri Moyo and Pumwani and close to Nairobi's industrial area and railway station. The police were outnumbered and could only watch as defiant workers congregated in the valley.
What had started as a protest by some unemployed youths backed by taxi drivers and prostitutes gained so much popularity that even the military, municipal council and electricity companies were affected.
The strike gave Kenya Africa Union a national appeal and popularised some of the militant trade unionists such as Fred Kubai who would later become a venerated freedom fighter.