The formal records of the French intelligence services of this period are partly available through French archives and partly not; the specific records of the Deuxième Bureau during the fall of France and the subsequent wartime period were subject to the disruptions of occupation and the deliberate destruction of sensitive materials. What survives in the archives is incomplete.
The contemporary American intelligence assessment — the judgment of Lieutenant Paul Jensen and others who worked in North Africa and who assessed Baker’s contribution as significant — is cited in multiple secondary accounts but the primary documents from which those assessments derive are not fully available in the publicly accessible record. The CIA profile that acknowledges Baker’s wartime service is itself a secondary account, drawing on the established historical record rather than on archival intelligence documents.
This evidentiary situation is not unusual for intelligence history. The nature of intelligence work — the deliberate concealment, the need to protect sources and methods, the records destroyed to prevent their capture by adversaries — means that the documentary foundation for even significant operations is often thinner than historians would prefer. What is established about Baker’s wartime service is consistent across multiple independent sources, corroborated by the formal French military honors she received, and treated as credible by historians who have examined the period.
The specific claims that require more caution — the precise quantity of intelligence she gathered, the specific operational impact of that intelligence on Allied planning, the exact formulation of the invisible ink on her sheet music — are claims for which the evidence is thinner, and they have been presented here with appropriate qualification.