28 March 1960
Oliver Reginald Tambo left South Africa shortly after the Sharpeville massacre, on the instruction of the African National Congress (ANC). The international world strongly sympathised with South Africa in the aftermath of the massacre.  Tambo left the country illegally to continue with the struggle from exile. Tambo left alone and arrangements were then made for his wife Adelaide and his children to follow.  Once they reached London, they initially stayed with South African exile, James Phillip. Soon thereafter they moved into a small flat and Adelaide found a job as a nurse. The family returned to South Africa in 1990.
References

SAHO, African National Congress Timeline 1960-1969, from South African History Online, [online], Available at www.sahistory.org.za [Accessed: 07 March 2014]|ANC, (1987), Oliver Tambo, from African National Congress, [online], Available at www.anc.org.za [Accessed: 07 March 2014]