Dave, you're PM, not a chat show guest
Why did he do it? Why did the PM go crawling to the US? Isn't there just something inappropriate about our leader reducing himself to a late night turn on TV?
The fact that he didn't know what 'Magna Carta' meant or who wrote Rule Britannia pale into insignificance when compared to his unctuous fawning at the States. "Banging the drum for British business," we were told, as if being PM of Great Britain and Northern Ireland is little different from having a film or album to plug. It's all product in the end.
Could you imagine Barack Obama appearing on The Graham Norton Show or Alan Carr: Chatty Man? Even his defence of Larry, the Downing Street cat, was half-hearted. Getting in help indeed! As if cats over here aren't up to the job! Maybe we should get an American cat to show us how it's done. Remember your British reserve, Dave. Stiff upper lip and all that.