Andrew Marr on his 18 minutes with Barack Obama

Andrew Marr interviewed Barack Obama at the White House in Washington DC

The chance to interview the president of the United States does not come around often, and the BBC's Andrew Marr fights the nerves as he hacks back his long list of questions again, and again, for his 18 minutes with Barack Obama.

"He's way behind schedule."

We were sitting in the BBC's Washington bureau waiting to watch Barack Obama's foreign policy speech at the State Department. An hour or so later we were to present ourselves at the White House for his first British television interview in ages.

My deep dark streak of east-coast Scottish pessimism was already telling me we'd be cancelled. At the last minute. The man is busy, after all.

He was running half an hour late, and it was clearly a frantic day. In his speech President Obama mentioned the controversial 1967 Israeli borders as the basis for peace talks with the Palestinians.

'Bibi' Netanyahu, due the following day, wouldn't like that. I scrubbed out a question I'd wanted to ask, and substituted another. The Israelis must be calling him already.

Technical set-up

As we clambered into the taxi, I was still half-expecting an apologetic call from President Obama's people.

But no. With Barney Jones, my producer, and Simon Wilson and Brian Gottlieb from the bureau, who had worked like Trojans to get the interview, we were ushered through to an oval room overlooking the White House lawn.

It's called the diplomatic room, because ambassadors present their credentials there, and it's decorated with wonderful French scenes of America, done in the 1830s.

We had already made a terrible mess of it, with three cameras and all the wiry gubbins that goes with them. Earlier on, a barefooted Michelle Obama had passed through and mused that whoever all this was for, it wasn't her.

There was a long wait. The Obama team had checked everything and warned us repeatedly that he was very tight for time. There would be 18 minutes for the interview and two minutes to walk and talk along a nearby corridor.

Was I nervous? I have interviewed prime ministers, foreign leaders, royalty and rock stars. Damn right I was nervous. You don't get an interview like this very often.

I had, of course, a long list of things I wanted to ask about. The shortened list of questions would fill an interview of say, an hour and a half. If we got short answers. The president is not known for short answers.

I'd hacked back and hacked back. In my mind, that is - I hate interviewing with notes on my knee; it's far better to keep eye contact.

Time issues

At last he arrived. We'd been warned he was tired, but he arrived with a broad beaming smile. As we sat down, I told him I'd be starting with Osama Bin Laden before we got to the big issue of the week, the Middle East.

"Andrew, you can start with whatever you want," President Obama replied: "You've got 18 minutes."

Next door, Barney and the White House communications team were listening and watching. I had a wireless earpiece so I could hear how many minutes had gone and keep to time.

Just after Barney whispered, "five minutes gone" there was an audible "phut" and the link went down.

The inevitable result was that I overshot my allotted time. Apparently people were jumping up and down next door; for us the only problem was that we lost our meant-to-be-relaxed-looking walk and talk down the corridor.

Not so bad. It's a great shot for personal PR but I'd trade that any day for another question or two.

What was he like to interview? Very focused, very clever. Once or twice he saw where I might be heading, and expertly headed me off at the pass.

Once I got a steely look and a "that's enough of that" kind of answer. He grinned at a couple of the questions, and was as nuanced, careful and balanced as his reputation suggested.

But he wasn't bland. Two or three times he gave me much crunchier, newsier answers than I was expecting.

Blues bar

Afterwards, we reeled off and did the endless pieces to camera and radio links that a big interview needs to be properly packaged for the BBC world and home audiences.

I'd come across from covering the Queen's visit to Ireland and by now I was dog-tired and rather stumbling.

I showed the interview to Mary Jordan of the Washington Post and Jamie Rubin, who served at the State Department under President Clinton. What did they think? They were both impressed by what he'd said about the Taliban, and about Israel. Phew.

By mid-evening I had stopped kicking myself for all the questions I wanted to ask and never got to, and a few beers were disappearing rather smoothly.

It was off to a blues bar in Georgetown and a day that ended rather more hazily than it began.

President Barack Obama's interview can be seen on the Andrew Marr Show on Sunday 22 May at 0900 on BBC One.