Didn’t MI6 help create the OSS?
In this Wiki about the OSS...
President Franklin D. Roosevelt was concerned about American intelligence deficiencies. On the suggestion of William Stephenson, the senior British intelligence officer in the western hemisphere, Roosevelt requested that William J. Donovan draft a plan for an intelligence service based on the British Secret Intelligence Service (MI6) and Special Operations Executive (SOE). Donovan envisioned a single agency responsible for foreign intelligence and special operations involving commandos, disinformation, partisan and guerrilla activities.[6] After submitting his work, “Memorandum of Establishment of Service of Strategic Information”, he was appointed “coordinator of information” on July 11, 1941, heading the new organization known as the office of the Coordinator of Information (COI).
Thereafter the organization was developed with British assistance; Donovan had responsibilities but no actual powers and the existing US agencies were skeptical if not hostile. Until some months after Pearl Harbor, the bulk of OSS intelligence came from the UK. British Security Co-ordination (BSC) trained the first OSS agents in Canada, until training stations were set up in the US with guidance from BSC instructors, who also provided information on how the SOE was arranged and managed. The British immediately made available their short-wave broadcasting capabilities to Europe, Africa, and the Far East and provided equipment for agents until American production was established.
https://en.wikipedia.org/wiki/Office_of_Strategic_Services