IoS Appeal: Sarah was a runaway, escaping abuse and jumping trains. Now, at 16, she has a new life

She is now a confident 16-year-old woman with a future, hunting in Gloucester's shoe shops for the latest baby-blue Timberland boots. But Sarah Williams is lucky.

Not too long ago, Sarah was a very different girl. She was a habitual runaway, at war with her older sister and angry with her mother, she rarely washed or changed clothes, leaving her bullied and friendless at school.

It was all triggered, she said, by a history of sexual abuse by a local man - abuse which she alleges had gone on unreported for nearly five years. Several years ago, she broke her long silence over the abuse, leading to a crisis with her sister and mother.

Sarah, then 12, began running away, heading aimlessly into the city at night, sleeping on floors and - in the most dangerous adventures of all - taking train journeys across western and central England.

She "jumped" trains to Manchester, Stroud, Bristol and Chepstow. She became another statistic - another of the 100,000 children who run away from home each year in Britain. Most return unscathed; some, like Sarah, face the very real risk of falling into drug abuse, homelessness and, worse still, prostitution.

But living in Gloucester made her lucky. Unlike most major British cities, the West Country town is the base for a runaways project called Astra that is funded and supported by the Railway Children, the charity chosen for this year's Independent on Sunday Christmas Appeal.

The Railway Children is unique. Alongside its pioneering work with railway children in India and Russia, it specialises in funding several projects in the UK for runaways, including critically important schemes in Glasgow and a project with Roma children - children who find themselves begging on the London Underground.

Sarah was rescued by Astra. Its small team gave her the unconditional security and support that she needed. Sitting with the Astra workers, she said, is "almost like two friends sitting and talking. I know they won't go and tell my mum what I'm saying." They helped her rebuild her self-esteem, to heal the scars of the sexual abuse and, crucially, to reunite her with her mother. "I just wanted to run away from all my problems. Most stuff which happened to me, happened around this area. If I ran away from here, I can run away from my problems. Now I know it just doesn't work like that," she said. Despite these successes, the Railway Children and the Astra project desperately need your help. There are thousands of children each year - including hundreds in Gloucester alone - who are just like Sarah.

Take Lisa, now 15. She had planned to sit with Sarah last week and talk frankly to The Independent on Sunday about her life as a runaway. But Lisa is instead in hospital. Last Saturday, she had a severe emotional crisis - and was considering suicide.

That morning, she called the Astra project from a park near her home, barely a day after being given a double dose of Prozac by her doctor. She explained that the drugs weren't working and that she had begun cutting herself. "She said she wanted to die, that she wanted to kill herself," said Hattie Darkin, the Astra project's co-ordinator.

Her doctors are now trying to get her placed in a specialist child psychiatric unit. "Her self-harm on Saturday wasn't a suicide attempt but she felt that self-harm wasn't working: it wasn't enough of a release," Ms Darkin added.

Lisa's emotions are extremely fragile. The latest trigger was the break-up of the relationship with her boyfriend. "She is consumed with self-loathing, consumed with anger and just in a terrible state really," she said. "She was very confused on Saturday and wanted to die; wanted to self-harm. But she does value her life; she's just in a mess."

At the root of Lisa's crises is her parents' separation in 1999. Deeply distressed by the break-up, she is violently angry towards her mother and unable to live with her father. She has also now fallen out with her foster carers - finding it impossible to settle.

And then there is Neil. He began running away at 10 - escaping from his alcoholic father and his regular drinking bouts with alcoholic friends. Those sessions led to verbal and physical abuse of Neil, so he would just "head off" on to the streets and the local railway station.

On several occasions, "he was so fed up with everything, he thought he would just take himself on holiday", said Ms Darkin.

The youngster had a fantasy about reaching Weston-super-Mare, where he had once enjoyed happy family holidays - holidays when his mum and dad, now divorced, were still a couple.

His attempts to reach Weston - sometimes with a friend, a 12-year-old girl, in tow - would lead him to alien cities: Bristol and Reading. He would be picked up on station platforms, looking lost, by British Transport Police.

Now 12 and in foster care, he still runs away. He will run back home to his dad, only to escape again from the drunken abuse.

Neil will be spotted cadging cigarettes in local pubs, still gravitates to Gloucester's most notorious park, and once lived in a squalid squat - exposed each time to the risks of abuse, child prostitution and drugs.

His parents' separation, said Ms Darkin, is a classic trigger for many young runaways. "He just loves his family to death," she said. "People just underestimate the impact that separation and divorce can have on the kids."

And Sarah is proof that this project succeeds. Now a proud and engaging young woman, she wants to be a youth worker, and is now studying at a local college for a health and social care qualification. "I say 'never give up'. There's always someone who's gone through worse, and always someone who can help you," she said. "We're not victims. We're survivors."

Some names in this article have been changed