For the British press corps, the Philadelphia visit by Prince Charles and the Duchess of Cornwall raised some questions and evoked a little-known bit of royal history, but for them it was more of a photo op than a headline maker.

Altogether, half a dozen British newspaper reporters, a gaggle of photographers, and a BBC-TV crew followed the couple around the city yesterday.

The questions surrounded the size of the royal motorcade - 17 vehicles - which probably had to do more with the security concerns of the hosts than the wishes of the guests.

At issue is an ongoing story in Britain about the prince's "carbon footprint" - the amount of greenhouse gases generated by his travel in private planes and other activities - and Charles' stated efforts to reduce it, including canceling a recent skiing trip.

That's a key reason the couple flew to Philadelphia on a commercial jet. But even then, reporters said, the fact that his entourage took up all of first class and business class on the plane raised some eyebrows back home.

James Bone of the Times of London said that meant the "best part" of the weekend trip would come tonight - when the prince receives an environmental award at a star-studded event at the Harvard Club in New York.

He said royal handlers also had made it a point to note that the prince and duchess were traveling by electric-powered train to New York.

Bone said he chiefly had come to Philadelphia for material for his first-edition story for tomorrow's paper, which he will sub out with details from the awards dinner, if it doesn't bang up against his deadline.

Bone noted, though, that there was a detail of the Philadelphia trip that could not be overlooked.

Seems that Charles' great-great-grandfather Edward VII, who was Prince of Wales when he visited Philadelphia in 1860, had a mistress who would later become the Duchess of Cornwall's great-grandmother.

Last night, the royal couple sat in the same box where the Prince of Wales sat 147 years ago.

"It's a bit of karma," Bone said. "It's got a romantic element to it."

Andrew Clark of the Guardian said he was interested in seeking out the reaction of locals to the royal visit.

"I want to know if they think visits like this are valuable," he said, adding the reaction had been "mainly quite positive."

But he and Bone said they also had heard residents in Mantua - where the royals visited a mural - say they had not seen their neighborhood so clean in a long time and that while the mural is nice it can hardly conceal the poverty and crime around it.

But all in all, Bone said, in terms of royal trips, "this is not very high-key."

Contact staff writer Joseph A. Gambardello at 215-854-2153 or jgambardello@phillynews.com.