These statements, made by the authoritative historian of Lend-Lease and the RAF C.-in-C. in the Middle East, respectively, point to the dichotomy that remains at the core of American supply to Britain. Kimball's observation reflects the axiomatic understandings of conventional historiography, while Tedder's statement reflects the frustrations he felt as the primary beneficiary of American aircraft supply to the RAF in 1941–2. Both these statements are true but require reconciliation, or at least some form of quantification, to learn the extent of contemporary British dependency upon American supplies.

By the spring of 1941, the British had apparently achieved their main objectives with regard to American supply. The 1940 purchase programme had occupied most of the available capacity of the American aircraft industry. Future production seemed to have been secured as a result of Lend-Lease while the Slessor mission had established an agreed plan to allocate up to 50 per cent of that production to Britain. The total number of American aircraft ordered was certainly impressive – over twenty-two thousand by the end of 1940. Resistance from the USAAC to British procurement and allocation had apparently been addressed by the high priority afforded to the British by the administration and development of personal contacts between the United States and British services which culminated in the Arnold mission of April 1941.