Cameron was happy to respond with his own insult about the work Romney did with the Salt Lake Games.
"We are holding an Olympic Games in one of the busiest, most active, bustling cities anywhere in the world. Of course it's easier if you hold an Olympic Games in the middle of nowhere," Cameron told reporters in London.
It wasn't the most stellar moment for Romney, whose campaign had hoped the London Olympics would provide a stage for the candidate to remind American voters of his success in turning around and leading the Salt Lake Games 10 years ago.
And Romney's off-the-cuff remarks didn't much help the trip's objective of boosting his foreign policy credentials.
"If Romney's goal of this trip is to show he's good at diplomacy and promoting U.S. interests, this is a lousy way to show it," said Thad Hall, an associate professor of political science at the University of Utah.
Mark McKinnon, a former senior adviser to President George W. Bush's re-election campaign, also flashed a thumb's down.
"Romney went across the pond meaning to stick his toe in some foreign policy and instead stuck his foot in his mouth," says McKinnon. "Not an auspicious beginning to his trip."
On the other hand, Salt Lake City Mayor Ralph Becker saw the humor in being dragged into the rhetorical spat.
"I would welcome Prime Minister Cameron to come to Salt Lake City," Becker said. "We would treat him royally and show him what the middle of nowhere looks like."
Becker said he thinks the back-and-forth between Cameron and Romney is a "little silly" but that Salt Lake City residents know very well the difficulties in putting on such a large gathering as the Olympics and it's fine if Cameron hasn't had the chance to pull out his globe and pinpoint Utah.
Hall saw that as saavy politics on Becker's part, perhaps using the incident to promote tourism and exports to Great Britain. It could, he noted, help put Utah on the map.