The RAF wing commander isn't ever going to be the captain of any aircraft in use as Air Force One - perhaps on the roster as a reserve co-pilot but I doubt that as well - far more likely he might be on flying duties with other aircraft in the 89th Airlift Wing fleet.
The captain of Air Force One - The Presidential Pilot - is a colonel (OF-5) post and has been ever since 1948 as the responsibilities go way beyond being the captain when flying the aircraft - as can be seen in this Nat Geo documentary from Col Tillman's era.
List of Presidential Pilots (minus the current one) - Presidents Truman > Obama:
https://www.iloveairforceone.com/history/pilots/
Nat Geo documentary: