It is 7pm on Monday night, and the strain is beginning to tell on Michael Autieri, the middle-aged manager of the Pro Sports shop in the Station Square shopping mall in downtown Pittsburgh. Told by the secret service that the President of the United States and the British Prime Minister will be visiting the store on their walkabout, Mr Autieri has been waiting for a full hour since the designated time. He has three television crews waiting with him. He and his staff have run out of conversation. He, at least, knows who the VIP with Mr Clinton is. (A shopper in the mall, when asked if she knows, replies: 'Yeah, but I can't remember right now.') Mr Autieri produces, while we wait, one of the few items of clothing with a British connection. Unfortunately it is a sweatshirt with the legend: 'England - World Cup USA 1994'. Wisely, perhaps, he puts it away when the First Shopper and his guest finally arrive.

In Mr Autieri's sports shop we learn something of the different styles of Bill Clinton and John Major. Mr Major casts round for something to buy - with the slightly paralysed expression of a man trying to find a loved one a present 20 minutes before the shops close on Christmas Eve. For no apparent reason he alights on a blue 'Mighty Ducks' ice-hockey team shirt, which he buys for his son James. Anyway, explains Mr Major, 'whatever I find, my son will steal.' It costs dollars 69 and Mr Major does not have the money with him, so Christopher Meyer, his urbane new press secretary, pays.

The President spots a Pittsburgh Steelers baseball cap, smiles, strides over to it and back to the counter. He takes out his wallet, hands over a 50-dollar bill and gets a 20-dollar bill in exchange. The transaction looks utterly natural.

Which brings into relief what Mr Clinton has and Mr Major hasn't. The Clinton political skills are as formidable in public as they are known to be in private. An hour earlier the President had bounced confidently on to the stage of the hangar at the Pittsburgh air-force reserve base, ahead of the British Prime Minister, and palpably turned on an audience of 2,000 local democrats, US air employees, labor union stalwarts and their families. Mr Major stands beside him a little awkwardly, his speech notes visible in his coat pocket.

Historically, this is a blue collar town. But it is changing fast, as the sunset industries - notably steel - give way to the services and high technology. The audience could hardly have been warmer; David Bratnick, an experimental machinist and president of Local 630 of the International Union of Electricians, has read in his local paper about John Major's Pittsburgh connections - how his brother Terry recalls being told by their father of searching for sarsparilla root to make soft drinks. Now he plans to send the Prime Minister cuttings from the sarsparilla plant he has at home. The audience - a transatlantic microcosm of the classless society that is Mr Major's dream for Britain - are on his side, warmed up with expertise by the President.

And so they remain. Mr Major's speech is unthrilling but graceful; what he lacks is the Clinton magic. It is easier for Clinton, of course. He is on his home turf, if not in his home state. He is a head of state. All this helps. But there is a powerful sense that Mr Clinton, who goes on to tour the shopping mall with Mr Major, to watch a spectacular fireworks display from Mount Washington - with dazzling firework formations of the Stars and Stripes and the Union Jack on the banks of the Monongahela river - is doing little more than showing his kid brother a good time for 24 hours.

Still to come, after the dinner at the hilltop Tin Angel restaurant, is the trip on Airforce One, the huge personal toy that grown-up presidents have - the Boeing 747, with its office suite, its double beds, its telephone at every seat, its medical bay. There is something symbolic about the way it dwarfs the 35-year-old VC10 on the Tarmac at the air base. Then there will be the night in the White House's Lincoln Room, and the brief meeting with Hillary when the three gather for breakfast after the President's morning jog. The briefing for the White House press corps says that Mr Clinton and Mr Major have agreed to meet in Pittsburgh, 'on Mr Clinton's suggestion, in order to get away from the structure of an official Washington visit and because of the Prime Minister's family connection to the area'. But what does this mean? Is Mr Clinton taking this visit, well, seriously? And should the Brits have gone along with it?

What's more, Mr Clinton even managed to take in a little local politics in the Pittsburgh trip. He has flown in from Chicago, where he went as much as anything to give some much needed public support to the beleaguered Dan Rostenkowski, who is facing a difficult primary election this month, is caught up in a federal criminal investigation into the alleged misuse of funds, and whose survival as chairman of the all powerful House Ways and Means Committee is vital to the progress of the President's health care reform package. (The New York Times on Tuesday went so far to link the two trips, suggesting that the President 'divided his time between two political leaders in political peril' - gratuitously pointing out that Mr Major has watched his popularity rating decline to 13 per cent.) And it just so happens that Senator Harris Wofford, who chaired the Pittsburgh rally, is a Democratic Senator up for re-election in November.

But it is surely the President's acute political sense that shows there was something more in this visit. When President Clinton showed Mr Major round the White House for half an hour after their return from Pittsburgh they talked, we are told, about 'personal stuff' including their children and their own childhoods, both in very different ways shadowed by unhappiness. They had some politicians' talk about health care and about the problems both have had with their national legislatures. But the talk on foreign policy issues was deadly serious. Major and Clinton said goodbye understanding each other better on Bosnia, on Russia and Ireland than before the trip took place.

Just before he left Mr Major was asked whether he ever wished he was a president rather than a prime minister. Mr Major replied: 'No, I enjoy the job I've got, but I wouldn't mind the plane.' It was a good and harmless joke but for some reason the second half of the sentence has been excised from the official Central Office of Information transcript of the interview. Perhaps Mr Major should take a lesson from Mr Clinton and loosen up.

(Photograph omitted)