Gus O'Donnell's gaffe in expressing his frustration that there's no one to talk to at the US Treasury - "There is nobody there ... You cannot believe how difficult it is" - is evidenced by this key personnel page from the US Treasury's Office of Economic Policy:
One imagines O'Donnell calling all possible extensions, as one does, ... 622-2201, 622-2202 until he reaches the department's Janitor
"Ain't no one here, sir"
"But this is the British Prime Minister's office. I need to speak to someone urgently"
"You can leave a message on the website, sir. Which church are you minister of? I ain't never heard of you .... Britt Ekland? Yeah, I saw her once"
"Yeah OK I'll write a message on a post-it and leave it on the Assistant Secretary's door. You're Circus McDonald and you're calling about the world economy. OK, sir, I'll pass that on ..."