They might have been from Mars: 'They enjoy breakfast cereals, fresh fruit and vegetables. They like the Radio Times, catalogues, DIY and record stores. Pet food fascinates them. They have no medical insurance. We won't know their names, sexes or ages nor the date they'll arrive. But, if you need any more information, please ask.'

A taste of our instructions for the care of our Russian guests. We were talking to students and teachers who had taken part in the previous year's exchange between School 42 in Moscow and the London girls' school Godolphin and Latymer in Hammersmith.

After much uncertainty, the host families finally heard that the Russians were coming. Our daughter drilled her Dad in words of greeting phonetically written. 'Zdrazdvoitye' he chanted. 'Minya za voot Ivan'; 'Hello. My name is John.' Before long it became garbled, like Chinese whispers.

At Terminal Two, someone's older brother saw the group approaching. 'They're wearing pink and blue pastels, like children,' he said, amazed, 'us lot are in good colours - like black.' A teen culture chasm to be bridged, along with language, food and culture shock.

It was as though our visitors had stepped out of the Fifties, from their clothes to the wrapping around the chocolates they brought. Both parties to this exchange were about to begin an intense learning experience. Deep friendships were formed that did not relate to judgements about appearance. We found that otherness mattered least.

The school took care of sightseeing 'musts' and the families filled in the rest. Some choices were unsuccessful. A French group earlier in the year had adored Camden Market, coquettishly trying on weird hats, scarves and earrings. But the Russians were unhappy there.

They were unmoved by quick-fix amusements such as videos and computer games. Their friendships seemed intense, their entertainment drawn from inner resources. Said one parent approvingly, 'Our guest can talk intelligently on the psychology of Pushkin.'

Our daughter and Natasha chatted easily, united by a lingua franca of youth: jeansi and bootsi are understood and desired by all teenagers. They dropped barriers of language as they sat together on the piano stool, playing and singing Beatles songs. Common ground was found in other music, be it djazz or classicheskaya musika.

Discussions about current affairs were cautiously handled: Westerners were always asking eagerly (and was it a touch paternalistically?), if things were 'much better now?' The questioners stressed freedom of speech and emphasised food shortages, which the Russians seemed anxious to play down.

Standing on their dignity they took a 'cool' position on the dramatic events that had led to these visits becoming possible. Natasha's father is a molecular biologist and her mother an engineer. They were managing OK, she said. Our lifestyle seemed at times both superficial and ostentatious.

At the school's evening entertainment we were treated to a scene from Romeo and Juliet in heavily accented English, impressively learnt by heart. There was emotive rendition of Russian composers on the grand piano - Natasha, playing superbly. Folk songs accompanied on a guitar by the lovely Sasha held us solemnly appreciative until a translation of one of the songs introduced some heavy humour: 'Your face looks like last year's potatoes.'

One of the only three boys on the trip went through a karate demonstration poker-faced and grunting, despite some suppressed giggling from the largely female audience. Their teachers clearly had had a hand in the programme.

The British contribution was in the panto genre, spiced up with some extreme costumes. The girls thought it up themselves. There was a Roald Dahl version of Cinderella and a brief reading of T S Eliot. Finally there was a mime to a Guns N' Roses number with the protagonists wearing long ratty wigs and bandanas.

The teacher leading the Moscow group made a formal speech and summoned Romeo with a flick of the wrist. He carried in a vast silver samovar and handed it to our tiny headmistress. Our gift to them was a much needed set of Russian/English dictionaries - practical, but not quite so dramatic.

The fortnight rushed by to become a swirl of memories: 12 teenagers walking down Whitehall after a show, singing 'Rule Britannia' and 'God Save the Queen', mingled with Russian songs in the quiet street; the Rock Island Diner where waiters stood and sang on tables and a chef from Moscow sang 'From Russia with Love' to the visitors; the day in Oxford followed by Starlight Express - from the sublime architecture of a bygone era, to the lasers and roller-skating world of Lloyd Webber. Was that bewilderment or enchantment in Natasha's inscrutable expression?

We wandered among the azaleas of Richmond Park and strolled along the riverside in Twickenham with kebabs in our hands. 'Frankly speaking,' she said, in her formal English, 'the air is so clean.'

There was a last visit to a supermarket, Boots and a Body Shop. (They have few cosmetic products.) 'Choose anything you like,' I said. She chose only bananas and a bag of kiwi fruits. Then added a punnet of strawberries.

Their certainty that Western goods would be stolen if left in cases in the hold, meant that all new clothes were worn on the day of departure. The youngsters, now resembling Michelin men, struggled with the Aeroflot authorities in stifling heat over the extraordinary weight of their hand luggage. We had given Natasha gifts. She held on fiercely to the bag containing BBC Poetry Please cassettes and books. She also clutched the banana/kiwi/strawberry purchase. She wore two pairs of jeans, T-shirts, a jumper and an anorak. She became flushed and anxious. I felt a motherly concern.

Finally they were gone - with emotional scenes and promises to meet in December for the return visit. We returned home to our gifts of vodka, Russian shawls with fluorescent roses, and lacquered spoons. But the greatest gift of course was intangible.

(Photograph omitted)