So this is what the Prime Minister said to me as I interviewed him on the roof of the Stock Exchange in Ho Chi Minh.
"Look, this is very testing, I accept that, because you have got a swarm of people coming across the Mediterranean, seeking a better life, wanting to come to Britain because Britain has got jobs, it's got a growing economy, it's an incredible place to live."
Now that word "swarm", in the context of migrants, is one that raises hackles.
The Refugee Council have called it "awful, dehumanising language from a world leader".
Andy Burnham said it was "nothing short of disgraceful".
Nigel Farage quickly said he wouldn't use that kind of language, before it was quickly discovered that he once had.
For what it's worth I don't get get the sense that Mr Cameron had thought about the term in advance, and he certainly didn't repeat it in later interviews. But from the reaction it has been getting so far I think he may be hearing it again and again.