Nelson Mandela once told a gathering of international reporters: “You are privileged people. You can observe from near but judge from afar.” But for George Alagiah, this kind of disassociation was never possible. Born in Sri-Lanka, brought up in Ghana, and settled in England, he says that he has lived his whole life as a migrant. Formerly one of the BBC’s leading foreign correspondents, and now the face of the Six o’clock News, his career abroad has put him in the middle of some of the most significant events of the last decade.

Entering the BBC TV Centre in White City, I half expect to see Alagiah beaming at me from the plasma screens that line the reception. I’m greeted instead by Sophie Raworth presenting BBC News at One. Moments later, the man himself strides through the interior swivel doors. Ms Raworth’s televised reception just doesn’t compare.

His career in journalism began at Durham University. There was no climbing the ladder; he applied straight for the position of editor at the Palatinate student paper and got it. After that, his degree in politics was somewhat sidelined, and as Alagiah puts it to me “some people might say I read journalism really”.

But he didn’t make the BBC’s graduate trainee scheme. Instead he took a job as Africa Editor of the now-defunct magazine South. It was this experience that really shaped his journalism, he says. It was an attempt to look at the world from a southern perspective; “the poor world’s perspective. The world looks very different if you stand in Managua, Harare, or Mumbai.” He explains how the magazine was talking about issues like the Kurdish problem or the unfairness of trade agreements long before the rest of the world first picked up on them.

It is this sense of perspective that has always been Alagiah’s real forte, and so appointentment as the BBC foreign correspondent in Johannesburg in the 1990s was certainly no vocational detour. While stationed there he met two towering figures of the political world: Nelson Mandela and Desmond Tutu. I wonder what was going through his head in these encounters. As Alagiah recalls, the Mandela interview came when everyone wanted him. It was 1994 and the ANC had just won an election. “You were, whether you liked it or not, sitting next to a man of soaring moral authority. I had to curb the temptation to sit there and go ‘wow, I’m sitting next to Nelson Mandela’, and just get on with the interview.”

But while the experience was sensational, it was also one of the most challenging interviews Alagiah has done: “Mandela is a man who found it very difficult to talk in any personal terms. Of course this is half of what you go to an interview for. You want to find out what makes them tick and get something personal. But you couldn’t get him to talk like that.” Alagiah remembers Mandela’s eloquent explanation for this: “‘I learnt to think through my brains and not through my blood’.”

Tutu was an absolute contrast: “A man with vigour and a kind of impish humour. But the same kind of moral standards and goals”.

After almost two decades as a specialist foreign correspondent, I ask if he’s bothered by the parochialism of the mainstream TV news he now presents. There is inevitably some loss of intimacy with the stories; surely that’s the rub?

But Alagiah argues that there is a fundamental continuity: “OK, I no longer specialise in foreign affairs. But if you look at the job of a journalist, whether presenter or reporter, it’s to get an idea across, to boil down a story. And that’s still what I do.” He’s eager to expand on this point: “Most people think that presenting is the 28 minutes from six to when the program ends. I don’t regard that as my job.” The real journalism happens 2-3 hours before when he helps devise the program. “Right up until 5.30-5.45 what goes in is up for grabs.” He pauses, and then hastens to add: “But although it’s my program, in the end it is of course the editor’s call.”

Last year Alagiah made headlines when he was told to step down as patron of the Fairtrade Foundation charity. The media fuss threw up the issue of what it means to be an impartial broadcaster. “It is not the business of BBC journalism to take a view on this” said Helen Boaden, the BBC Director of News. I also flag up his position on the board of the Royal Shakespeare Company. But Alagiah assures me that he thinks no one, as yet, is against Shakespeare. All the same, he admits that striking a blanace between the personal and the professional is always a challenge. “We’re not cloned out of nowhere as presenters; we’re human beings, we live in the real world, and of course we have opinions”.

The thing is – and Alagiah is adamant that these aren’t confused – there’s a difference between opinion and judgement. “Nobody pays me to have opinions, or far less, broadcast them on air. Who cares what George Alagiah has an opinion about?” But he wants to be clear that senior journalists are expected to have some judgement. “You can’t have a half way house on everything. Where’s the middle ground between a woman that’s been raped, and the man who’s raped her? There isn’t. You have to make a judgement.”

Having now spent many years in our living-rooms, perfecting the BBC smile, Alagiah is also the Mr Nice Guy we all trust to deliver the bad news. And in Britain there seems to be a deluge of it. I ask how on earth he gets up every day to announce yet more deaths from the Middle East conflict, or that we’re all, yet again, doomed by the perils of climate change. He’s got to get disaffected by it all, surely? “Not at all,” says Alagiah. “Some stories get me more than others – but I don’t think I get bored with any of it.”

He also points out that it’s not all about the news. “We’re in people’s faces daily. People develop a relationship with you and the BBC.” And just occasionally he gets an email or letter where someone says, ‘Oh, you looked a bit upset the other day. Was anything wrong?’

The six o’clock news is on in a few hours and Alagiah gestures at his watch. I take a last look around the news room and it seems as though we’re sat among a vast workforce at his command. Maybe the Murdoch media czar image is a stretch too far, but I have to ask whether he thinks he’s clinched the best job in the BBC. “I’m not just saying this”, replies Alagiah, “but I pinch myself sometimes just to make sure it’s all real.”

George Alagiah speaks at the Union 19th May 2010 8:30pm