Found: The gap-year boy missing in Africa for months is held in Paris

And even as his parents exclusively told The Mail on Sunday of their relief, some worrying questions were emerging about the disappearance of former chorister Aydan Savaskan, 20, who had been in Kenya on an organised volunteer placement.

His story may serve as a stark warning to parents who think their children are safe on "structured" gap-year trips abroad.

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Aydan's adventure began to spiral out of control when he began drinking heavily, became involved in a series of arguments and fled his volunteer hostel for a seedy hotel.

Then he started travelling to countries known as staging posts on the drugs trail to Europe, while telling friends he was involved in "selling stones".

Scotland Yard had appealed for help when Aydan's parents raised the alarm after he failed to check in for his return flight from Nairobi. Sarah and Sinan Savaskan had not heard from their son since February.

But, last night, The Mail on Sunday learned that the former public schoolboy was in custody in Paris.

Aydan's parents have yet to learn the circumstances under which their son found his way into custody. But as their desperation subsides, some alarming questions are posed.

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Was a young man who seemed street-wise in Britain frighteningly vulnerable and lost, literally, in a distant continent?

Or did Aydan's bid to "find" himself, thousands of miles from home and unfettered by parental control, unleash something dark and rebellious?

Speaking from the family home in Herne Hill, South London, Mrs Savaskan said: "What happened exactly is still unravelling. Whatever he has done it doesn't matter. We love him and want him home.

"We had no reason to think Aydan was in trouble. But it appears that he got into some. Like all teenagers he went through a chaotic time but he'd come through that and turned his life around.

"We never saw him drink or smoke at home. He was a strict vegetarian and didn't drink for a year before going to Kenya. He was very calm the year before he went away.

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"We think he stopped contacting us because he hoped to alert us to the fact that he was in trouble and couldn't let us know any other way."

For Mrs Savaskan, a teacher for the National Childbirth Trust, and her Turkish-born husband, Sinan, a well-respected modern composer, the simple fact of Aydan's reappearance is a source of relief beyond expression.

They say Aydan's trip to Africa was driven by a desire to do something charitable before he embarked on a degree in Theology and Creative Writing at Lancaster University.

Aydan, who had been a pupil at the City of London School alongside Harry Potter-actor Daniel Radcliffe, arrived in Nairobi on September 15 last year.

His parents, who have three other children, had paid £1,300 for his sixmonth placement with Volunteer International Community Development Africa - a partner of the Global Volunteer Network.

As they waved their son farewell, they felt safe in the knowledge that Aydan would not be alone but would be living in a hostel run by the charity and working at a Nairobi children's home, for the first month at least.

And with internet connections linking him to home and to friends, his parents could almost believe he was not so very far away.

At first all seemed well. Mrs Savaskan recalled: "When he arrived in Africa we spoke to him every couple of days to make sure he had settled in.

"Once he'd settled in we were in touch once a week, or once every two weeks. He spoke to his friends over the internet every couple of days.

"We spoke to his friends and the volunteer organisation that he worked for. They both talked of him in glowing terms. He had no financial problems because we sent him a recommended monthly allowance.

"We encouraged him to set up a bank account so that he could draw on it slowly and not carry big wads of money around with him."

The picture that Aydan's parents paint is of a dutiful, thoughtful young man who sang in Southwark Cathedral Choir.

But another portrait of Aydan has emerged from friends and voluntary workers whom he met during his stay in Africa.

They describe someone with the best of intentions but a capacity for drink and troublesome behaviour and a rash streak that saw him leave the safety of his volunteer hostel and gravitate towards an altogether more seedy, shady environment.

After a couple of months in Nairobi, Aydan told Irene Wairimu, leader of the charitable organisation for which he was working, that he wanted a change of scene.

In hindsight it was the first indication of a restless instinct in the young man.

She said: "He was supposed to be here for six months. Until the end of November he volunteered at a Nairobi's children home and was living there with a group of volunteers.

"But then he said he wanted to go to a different environment and we agreed that he would go to the Masai from December 2."

Back home, there was no hint of any discontent and his parents had no reason to feel concern. As far as they were aware their son was having the most fabulous, and worthy, time.

Aydan wrote a letter home on that date, it began: "Africa!! This place is amazing, it fascinates me in so many ways and inspires me almost every day."

Yet even as he wrote this letter Aydan was showing signs of frustration with his Kenyan existence.

Paris Mwangi, the 26-year-old housekeeper at the volunteer hostel where he was then staying, explained: "The first few months when he was here he was so nice. But then he changed."

It was not a change for the better. Anthony Murdir, 21, who worked alongside Aydan at the orphanage agreed:

"When I met him he was a really cool guy, really polite. But he really loved to party and would get drunk, come back late at night and get into trouble."

At Christmas Aydan returned to the hostel but was involved in a disturbance that led to the police being called.

Miss Wairimu said: "Aydan and another volunteer had refused to pay a taxi driver.

"He smoked in the house and was disrespectful. One volunteer's mother who was visiting called me at 8am another morning to say that Aydan had come back very drunk at around 3.30am with a friend and they had been banging on the doors and the windows, waking everybody.

"The mother said she tried to speak to Aydan but he was very rude. That morning he left. He took his bag and he ran away before I got there."

Aydan's mother said: "If only we'd been told that by the hostel we would have contacted him and said, 'You're not enjoying yourself. Come home.'"

But Michelle Mettie, a volunteer from Mexico who worked alongside Aydan, and who described him as, "a very smart boy, very calm", with "a great heart," noted that he was also "very independent".

It may have been that independence that stopped him seeking help or guidance from his parents when the wheels began to come off his African trip.

Mrs Savaskan describes Aydan as a "great peace maker". She said: "He is a very peaceful person. He is very thoughtful, always made birthday cards and wrote poems inside and gave very thoughtful presents."

But no parent can know every aspect of their children's inner lives.

Miss Wairimu said: "When you speak to Aydan he appears to be a saint. But I don't expect behaviour like that from any volunteer.

"He was supposed to go back to the Masai land but he never went, despite being sent a letter to say he should go there and not go back to the volunteer house because of his behaviour. He never did come back."

Instead, on January 18, he left for a hotel in Ngara, a less salubrious part of Nairobi. The £10-a-night Moreland Hotel, is a renowned magnet for drinkers and undesirables - loud music pumps from its karaoke deck bar until late in the night.

While his parents in London believed their son was still working as a volunteer, he was telling Camille Simonese, a girlfriend he had met in Nairobi, that he was involved in "selling stones".

And, although his parents continued to send him £200 a month to live on, his hotel bill was paid by a local man. Today, the hotel manager insists that he cannot remember who.

The details of Aydan's existence over the next three months remain hazy but he was on the move and off the path that his parents had thought was set out.

He emailed Camille from the Hilton Hotel in Addis Ababa, Ethiopia on January 23.

Two days later, she received another message from him from Togo, West Africa where he said he had to meet "a contact".

Togo, like its neighbour Benin, is a known staging post on the narcotics trail from South America to Europe.

Camille received messages from Aydan from there until January 31 and felt uneasy at what she believed was his less than candid explanations about the business he was involved in. She said it sounded "shady".

By February 3 he was in Cotonou, the capital of Benin. Soon after, his emails simply dried up.

Daniel Strand, a Swedish volunteer who accompanied Aydan on many of his drinking expeditions, said: "The last I heard from him he had got a job delivering gemstones. I think he was in Tanzania or something."

When Aydan failed to turn up for his flight home from Nairobi, his parents were plunged into a maelstrom of anxiety that, truth be told, has not fully ended with his discovery in France.

But Mrs Savaskan insisted: "Aydan is not materialistic. He would never even take extra pocket money from us when he went out.

"Whatever he's done would not be for material gain. He is a kind man and vulnerable to emotional pressure. If he's in trouble it would be because he thought he was helping someone."

Last night, Scotland Yard confirmed: "Inquiries have established that Aydan was recently in France. We're satisfied as to his welfare. No further action will be taken by the Met."