They went to the Catholic Church of the Holy Ghost at Balham, in south London, and there, at 6.45pm, one of them saw and talked to the Virgin Mary.
Ivan Dracevic, whose sulkiness vanishes with his smile, is 27. Eleven years ago last June, on a rocky hill near the village of Medjugorje in what was then Yugoslavia, he and five other peasant children between 10 and 16 first saw the Virgin Mary, they said. She told them that she would appear to them every day at the same time - 6.45pm in whatever time zone they happened to be in. She said they would receive '10 secrets' not to be divulged to anyone until they were told to do so. The apparitions would end when they had received the last of the secrets.
Medjugorje was sceptical. The villagers, the children's families, the police and their priests thought at first they were fantasising or raving. They were reprimanded, threatened, questioned and medically examined. The Church in Rome kept its counsel. But Medjugorje is now famous as a place of miracles.
For two of the young 'seers' of Medjugorje - Mirjana and Ivanka - the regular apparitions ended several years ago: both are now married and have children. For the four others - Marija, Vitzka, Jakov (at 10 the youngest at the time) and Ivan (the oldest) - all of whom have had nine 'secrets', they have continued.
The Virgin Mary is said to speak with each of them every day, and they reply. She talks to them as differently as they are different people: to Mirjana, the brightest of them, who went to university in Sarajewo, she apparently spoke a good deal about the world. To Vitzka, who is curious and extrovert, she told the story of her life. To Jakov and Marija, who is thought the most 'spiritual' of the six, she showed Heaven and Hell; and she helps Marija to heal people.
At Christmas every year, she appears to all of them with the baby Jesus, and the first time this happened - Marija still begins to cry when on rare occasions she talks about this - the newborn baby apparently played peek-a- boo and finally winked at them.
When Mary talks to Ivan about himself, he told me in London on Friday, 'it isn't in a big way about my future or anything like that: she talks about the next week or the next month'. She - or the apparition - seems to adapt to the capacity and needs of each; but every day, and in the messages she gives them for the world, she always speaks of the need for prayer, for concentration, for quiet, for simplicity and for peace.
On that first day 11 years ago, the children had told the apparition that no one would believe them. Could she not send a sign? That day she had shaken her head; but the next day she told them there would be 'small signs' and one day - she could not say when it would be - 'a big and final sign'.
And the very next evening, when thousands of people had come from all over, a brilliant light is said to have appeared over the village just before 6.45pm.
By now, documented and photographed many times by some of the millions who have been to Medjugorje since, there are said to have been many other light phenomena never seen in the region before - many 'healings' too. But the strangest of all - seen repeatedly by villagers, priests and pilgrims - was a word appearing in 'huge flame-coloured letters' in the night sky: 'Mir', which in Serbo-Croat is 'Peace'.
All of this seems, of course, impossible; a tale invented by simple souls which turned into - or was turned into - a perhaps much-needed myth. But how does one explain the results of psychological tests which found all of these young people to be 'normal . . . with no psychopathological symptoms'?
And how to explain the countless medical tests, many of which concluded that during the visions their heartbeats remained normal, their eyes did not blink and could not see, their ears could not hear, and their larynx did not function although the muscles operated normally and they could be seen to articulate silently?
Yesterday, at a marquee in Aylesford, Kent, 250 young people celebrated the 11th anniversary of the first Medjugorje vision with a 36-hour vigil. Ivan attended with his spiritual adviser, Fr Slavko Barbaric, and an interpreter, Milona von Hapsburg, who has worked with the seers for the past seven years.
It sounds like a travelling circus, but whether one believes in the visions or not, somehow it is not - Ivan is different in those strange minutes and the difference can be felt by all present.
Fr Barbaric said: 'They were very simple children in 1981, and basically they remain quite simple today.'
Jakov, who now works at a shop in a town near Milan, drives 'like Italians do' and endlessly listens to rock, according to Fr Barbaric. 'He just loves his quite fast life. I told him this summer that I knew that if he could escape the vision, he would. But of course, he can't. And though he is such a little raver, he becomes quite incredibly sensitive when he sees people who are poor, or hurt.
'Having faith doesn't mean you can understand algebra.'