In September 1939, two days before declaring war on Germany, the British government evacuated over half a million children from London to supposedly safer areas in the country. Schoolchildren went there with their teachers and infants with their mothers. Immediately after the event (and ever since) the impact of the evacuation on the children--the hardships of some and the adventures of others--has been extensively researched, as has been the operation's broader social impact. Meanwhile, the policy ontology of the evacuation's organisation remains surprisingly under-researched. This paper explores how the planning for the evacuation developed in a brief period before the outbreak of the Second World War, in order to assess responsibilities for its shape and ultimate execution. At the core of this article is the evaluation of four sets of documents from the archives of the London County Council about the evacuation's planning stages in the 1930s. Contrary to earlier claims that the administration of the children's evacuation was not only a success, but also an excellent illustration of co-ordinated planning and execution, it will be the conclusion here, that not co-operation and co-ordination at government and civil service level made London's evacuation a logistical success, but the relentless drive by the London County Council, who pushed for the evacuation in the face of opposition from central government. (Contains 1 table and 53 footnotes.)