That's what friends are for

As Barack Obama and British Prime Minister David Cameron posed for one more photo opportunity on the balcony of the White House I found myself straining to hear what the band was playing. I thought it might be that great Dionne Warwick number, That's What Friends Are For. It wasn't, but it should have been.

Because quite apart from the huge international issues these men had to discuss - Afghanistan, Iran, Syria and the rest - any official visit brings political benefits to one side or the other and usually both. More often than not, it's the British Prime Minister who has most to gain, standing alongside the most powerful leader in the world and hearing him say how special the Anglo-American relationship is.

For us Brits President Obama is still the epitome of political cool and some of us winced at Mr Cameron trying to do casual alongside him at that basketball game. Both men knew what it was really all about, of course. They weren't in a swing state in your November election for nothing. And David Cameron won't have minded that on this visit at least he was the one doing the political favours. If some of Obama's critics think he's too left wing, then being best buddies with a right of centre ally is no bad thing.

Cameron said the first President he'd learned about at school was Theodore Roosevelt. Really? Before George Washington or Abraham Lincoln? But it enabled Cameron to say that today's President shared with Roosevelt, who just happened to be a Republican, a belief in speaking softly and carrying a big stick.

When I worked for Tony Blair I came to Washington on a visit like this. Clinton was President and Blair found himself having to sit up until three in the morning chewing the cud as Clinton loved to do. But the chance to have a lot of face time over several days was important to them both, and that's the real value of these visits. On that occasion too we were the ones doing most of the political favours because Clinton was in deep trouble over the Monica Lewinsky affair.

There are few really deep friendships between Presidents and Prime Ministers, but Clinton - Blair was one and Reagan - Thatcher was another. Obama - Cameron? Probably not. But they are there for each other when it counts. And that's what friends are for.

This is Lance Price for CBS News in London.