Nutter, 50, is inspiring a sense of optimism in the City of Brotherly Love these days. As a result Philly’s First Family, which includes his wife Lisa, 43, and 12-year-old daughter Olivia is giving putative Obama First Family a run for its money.

Quite by chance I bumped into him, the morning after Hillary's victory party when he joined her, Bill and Chelsea on stage at the nearby Bellevue Ballroom. It was in the Philadelphia landmark Little Pete’s Diner on Philly's Chancellor Street, where one of the waitresses whispered to me: "That’s our mayor."

Nutter was quietly taking his breakfast of oatmeal and coffee between giving a hug to a little old lady who was thrilled with Hillary win. He happily chatted about the way Philadelphia is changing for the better and the excitement of the election. But what, I wanted to know, was it like being the black mayor of a city that had fallen head over heels for Obama, the first black politician with a more than serious shot at the White House? "No trouble at all," he said. "None of this is personal, its professional and we are all mature enough to distinguish between the two" And if Hillary doesn't win the nomination - which he doubts - he will sign up for Obama in a heartbeat. “That’s the beauty of America, if he wins, I’m going to work hard to get him elected.”

A famously corrupt city, Philadelphia has suffered years of dodgy leadership from politicians prone to accepting back handers. It has also been horrifically mismanaged. In one extraordinary episode in 1985, a Philadelphia Police helicopter actually dropped military explosives on the roof of a house occupied by squatters and "back to nature" agitators. The bomb set off a firestorm destroying the entire block and killing 11 people.

Nutter is universally seen as a welcome break with the past.