It had been an action-packed week that left the teenagers, three Unicef officers and local and Hong Kong journalists exhausted. We'd trekked up and down gruelling hill trails in Yangbi county to visit impoverished farms and families, been dug out of a landslide on a narrow mountain road on our way to a township and had to listen to endless formal speeches.

We were now in the three-star Cassia Plaza Hotel in the regional capital, Kunming, and this was the last chance for the pupils aged 14 to 19 to have their say on the week's events before an early morning flight back to Hong Kong.

'We shared our feelings about the whole thing, not only about the trip but from the day we joined this programme, it was simply touching,' said Joseph Ho Yiu-jo, 17, from St Paul's Co-educational College, runner-up in the South China Morning Post's 2004 Student of the Year contest.

'My first impression at a meeting at Unicef centre [in Happy Valley] before the trip was that my team members were a bit passive and I might not click well into the group, but we had debriefings in the evenings and I felt every one of them had put their hearts into their work.'

It was a sentiment echoed by student after student, evidence that the short trip into unfamiliar surroundings had had a profound impact on their relationships with each other. Theresa Lena Chow, 17, of Diocesan Girls' School, said: 'It was really deep, it was very true and very touching. We seldom talk about serious stuff like this in school, even among friends, this was very precious.'

Unicef's Young Envoys programme, now in its seventh year, is designed to offer the chance to experience village life in rural China. They also take part in social service events and fund-raising activities and are taught the aims of Unicef and the United Nations Conventions on the Rights of the Child.

This year 40 envoys were selected from 100 applicants, 30 of whom were earmarked after training, camps and workshops to develop their leadership and communication skills, to join the $130,000 Yunnan trip - paid for by fund-raising and sponsor MTR Properties.

On Monday, August 2, the group set off from Hong Kong to Yangbi via Kunming and Dali for an adventure that, for most, would be the first time they had witnessed life in rural China.

It was an enthusiastic troupe that took to the road, Snoopy dogs and other cuddly toys dangling from backpacks and one team member travelling with a guitar for both impromptu sing-songs in airports and on coaches and a planned group performance for local officials. The itinerary was planned jointly by Unicef in Hong Kong and the mainland, with the local office and provincial government officials arranging transport, food and accommodation.

Unicef invested US$9 million between 1996 and 2000 in a poverty alleviation campaign called Local Planning and Action for Children (LPAC) run jointly with the central government, and it was apparent from the outset that they were very special guests. Every trip, however short, had a police escort and they were treated to the very best of local hospitality.

The lunch menu on their first full day in Yangbi included fish soup, sesame bread with red bean paste, fried pork fritters, leg of pork, crystal vegetable with cucumber, chicken, bean leaf with bean curd, steamed egg custard with ham, kidney bean salad, shredded bamboo root, sweet bread, followed by passion fruit, apples, pears and baby tomatoes. A small army couldn't have eaten it all, which many envoys found at odds with the images of hardship they expected in China's seventh poorest province, with 10 per cent of the population earning less than 300 yuan per person per year.

Welcoming speeches greeted the envoys at each stop and the teenagers' newly-honed communication skills were tested as they were obliged to reciprocate with votes of thanks in Putonghua.

Apart from visits to local LPAC-funded hospitals and clinics, trips included a meeting in Hexi town - an hour's drive away - with 10 pupils who had received scholarships from a Unicef-supported trust fund of 16,000 yuan set up to provide education for 100 girls who would have otherwise been forced to quit school.

Envoys visited their homes, travelling over treacherous terrain in four-wheel drive vehicles and then on foot, astonished to learn later that the pupils walked the one to two hour journey each way, each day.

With the team divided into four groups focusing on education, health (sanitation and environment), HIV/Aids and poverty, other visits were made to mountain families in receipt of LPAC funds, a village women's meeting, the Yi people of remote Shuangjian township 2,600 metres above sea level and Kunming Salvation Army's HomeAIDS consultation and service centre.

It was an exhausting but rewarding schedule, if choreographed by local officials highlighting only the best of the worst.

So what had the Young Envoys been so frank about that last night in the Cassia Plaza hotel?

Well, the food was a major beef. 'I was a bit upset that we had such sumptuous meals,' said Lester Fung Ka-kei, 17, of Li Po Chun United World College. 'Some of us thought it wasn't suitable. There was so much and often we couldn't finish it, and it made me upset when I thought of those kids who didn't have enough to eat.'

Delphine Tse Hoi-yi, 17, St Paul's Secondary School, agreed: 'I couldn't help thinking that we were spending a lot on our accommodation and food while people in the villages had very little.'

But Joseph Ho pointed to the mainland tradition of hospitality, irrespective of wealth: 'I felt that they were giving us their best. This is a very Chinese thing that no other culture can perhaps comprehend.'

On the positive side, though, the interviews with the 10 pupils and mountain families had made a lasting impression.

'A farmer's daughter who received a Unicef scholarship had prepared a speech for us but was so touched she couldn't read it. 'We won't let you down,' was all she said and started crying. I'm not a very sentimental person but I was very moved by it. It was the most touching moment in the trip,' Theresa Chow said. 'It made me realise that being able to study, being able to go to a university is a very, very precious opportunity, and that we are very fortunate to live in Hong Kong.'

It was a reflection on Hong Kong shared by Phoebe Mui Hoi-ching, 17, from Sacred Heart Canossian College, who said: 'When I asked one of the pupils what she wanted to do she didn't want to tell me at first because she didn't want her parents to feel sad because they couldn't afford to pay for her dreams.

'But later she told us she wanted to study music. I was ashamed because in Hong Kong if I want to learn something, like a new language, I always ask my mum for the money because I think it's her responsibility to pay for everything I want to do. The girl I was visiting may have been younger than me but I think she was much more mature.'

Other highlights were the family visits. Joseph Ho: 'I didn't expect we would be able to go so deep into their feelings.' Lester Fung: 'It gave me a real insight into the living conditions.'

On the HIV centre trip, Amy Chan Yim-ting, 15, Tsuen Wan Public Ho Chuen Yiu Memorial College, said: 'A volunteer who was an ex-drug addict told us how he gave up taking drugs and became a helper. He said he wanted to tell all Aids patients that there are people who care about them.'

All of which left Connie Tsang, who joined Unicef just four months before the trip, with mixed feelings.

'At first we thought the trip was a failure in terms of itinerary. But today I think it went quite well. I couldn't really have expected more with less than four months of preparation, and after the debriefing I really felt that we managed to do something - at least they feel they've learned something,' she said.

She acknowledged that the envoys had not been able to assess the real contrast between reasonably well-off and very poor. 'I purposely requested to see the contrast between an LPAC and non-LPAC place. I wanted the kids to be shocked by how they can make a difference by doing a little fund-raising. What we saw was like comparing Central with Causeway Bay.'

But Jason Li Yin-chung, 15, from St Paul's Co-educational College, summed up envoys' feelings that night when he reasoned that any aid was better than none at all amid such crushing poverty: 'My former principal used to tell me if you cannot make a wave make a ripple. This week really inspired me. We can increase awareness among other people, and that's very important because a lot of ripples form a wave.'