Complex sentence: Official Historian Margaret Gowing noted that "No doubt Akers had been picked for his personality and drive that had been considered so important and which he possessed in abundance"; but his ICI background led to difficulties when it came to dealing with the American Manhattan Project.
Split into simpler sentences: Official Historian Margaret Gowing noted that "No doubt Akers had been picked for his personality and drive that had been considered so important and which he possessed in abundance". But Akers' ICI background led to difficulties when it came to dealing with the American Manhattan Project.