Dear Ms. Biggins,
Thank you for posting your request on History Hub!
The Dwight D. Eisenhower Library (LP-DDE) may have copies of correspondence between Prime Minister Churchill and Eisenhower regarding the Duke of Windsor. Please email LP-DDE at firstname.lastname@example.org to request more information.
We also searched the National Archives Catalog and located Central Decimal Files, 1910 - 1963 in the General Records of the Department of State (Record Group 59) that may include diplomatic correspondence between the United States and the United Kingdom regarding the Duke of Windsor. For more information about these records, please contact the National Archives at College Park - Textual Reference (RDT2) at Archives2reference@nara.gov.
Due to the COVID-19 pandemic and pursuant to guidance received from the Office of Management and Budget (OMB), NARA has adjusted its normal operations to balance the need of completing its mission-critical work while also adhering to the recommended social distancing for the safety of NARA staff. As a result of this re-prioritization of activities, you may experience a delay in receiving an initial acknowledgement as well as a substantive response to your reference request from LP-DDE and RDT2. We apologize for this inconvenience and appreciate your understanding and patience.
In reference to NA RA 802 775057, this does not follow the format of any identifiers that NARA uses. Given that a letter from Private Secretary to the Sovereign Alan Lascelles to Military Assistant Secretary to the War Cabinet Sir Ian Jacob would be internal correspondence of the British government, we suggest that you contact the National Archives of the United Kingdom. The UK National Archives should also have Britain’s copies of records of any correspondence from Prime Minister Churchill to Eisenhower. We located an article in the Guardian referencing British cabinet files that they released regarding communications between Churchill and President Eisenhower which may be what you are referring to, although this article refers to communications in the 1950s rather than 1945.
We hope this is helpful. Best of luck with your research!