The unpaid volunteers began donating by plasmapheresis at the North London Blood Transfusion Centre, Edgware. Linked evidence NHBT0086659 - Letter from Marcela Contreras and Patricia Hewitt and Mahes de Silva to the Editor of the Economist Newspaper - 12 Oct 1987 Chronology Information Date: 1 January 1967 Chapter/issue Blood Products and Addressing Risk: Self-Sufficiency