This year's Festival ends with a Mexican-British love-in, as director Alejandro Gonzàlez Iñárritu and his star Gael Garciá Bernal banter before the screening of Babel, before the dicky bows and gowns of their Odeon Leicester Square audience.

Bernal, virtually an adopted Londoner, recalls the experience of sitting in the same cinema in 2002 when Amores Perros - the film that brought both men to the world's attention - won a Bafta.

Gael Garciá Bernal: I was sitting right at the back there, near the air conditioning. I think it was four years, five years ago.

Alejandro Gonzàlez Iñárritu: We were young then.

GGB: So I was sitting in the back, on my own. Alejandro couldn't come because he was afraid of flying then.

AGI: I know a guy in Mexico who gave me some drugs for this trip.

GGB: I will be outside afterwards and I will be selling them... I was in the back and Amélie was looking as though it would win. But then they said,"Amores Perros" . I was thinking "there must be someone to pick up the award. Not me". But there was no-one else. I stood up and it was the longest walk down. It felt incredible. In the end I was so nervous that I forgot to mention that I was not Alejandro.

AGI: In a parallel universe, I was suddenly the most hot, handsome director in the world.

GGB: People were saying to me afterwards, "You're so young to have directed and acted in this film".

AGI: And when beautiful women said this to him, he lied.

GGB: So I'm happy to tell you know, it was him. Alejandro is able to direct a movie.

AGI: But you know, now we have set the tone for a comedy. And it's not...

Iñárritu is right, of course. Babel is many things - dramatic, harrowing, provocative, and a piece of typically bravura storytelling by the director and his regular writer Guillermo Arriaga; but it isn't funny.

The film involves four stories, in four different countries, their connections revealed in increments: in Morocco, Brad Pitt and Cate Blanchett play an American couple escaping a family tragedy, only to be struck by another; two Moroccan brothers play with their father's new rifle, with disastrous consequences; across the Atlantic, the Americans' Mexican nanny takes their children with her when crossing the border for a wedding; in Tokyo, a deaf mute girl struggles to keep her sanity after the death of her mother.

"This is the last piece of a trilogy that I started with Amores Perros, and then 21 Grams" Iñárritu tells us. "It's a trilogy partly because of the structure - of parallel stories that collide, with characters defined by other characters, all struggling to survive; but mostly because the three stories deal with the same subject, which is the very complex relationships between parents and children. Beyond politics and social comment, that's what I'm really obsessed by".

The cast and crew were on the road for a year making the film, in three continents. "I was transformed by the experience", says Iñárritu . "I started doing a film about what separates us as human beings, and at the end I discovered I had made a film about what connects us - the borders, not physical borders, but the ones within ourselves, that make us unable to express love and unable to receive it.

"Government, religion, the media all teach us a lot of prejudice" he adds. "But you can break through this, by looking into the eyes of someone and speaking to them. At the end of making Babel, I felt a lot of compassion".

And perhaps that is the greatest achievement of his film - an encouragement to break through prejudice, and language barriers, to try to empathise just a little more. It's a good lesson with which to end a great festival.

Demetrios Matheou