Courtney became the centre of Beckie's life

In many ways, Beckie Williamson was a typical 13-year-old girl.

She liked clothes and spent forever doing her make-up before going out with her older sister. She smoked too much and drank more than was good at her age.

But Beckie also had to face a lifetime of challenges in just a few years and she did it with maturity and compassion, which belied her age.

When she was 12, Beckie got into a serious relationship with a boy just a year older than she was. It was not long before she found out she was pregnant, something she hid from her family for seven months.

When she was 13, she gave birth to a little girl who she called Courtney. By the time she was 14, Beckie was diagnosed with bone cancer. Despite intensive treatment, her cancer spread. By 15, she was told her sarcoma was terminal and she died just a few weeks after her 16th birthday.

Burglary

Beckie's biggest regret in life was that her daughter would grow up never knowing who she was. She said she was not scared of dying but of leaving people behind, like her daughter. It was this which drove her to make a legacy video for Courtney.

She started filming using the family's video camera, but when it was stolen in a burglary she couldn't replace it. At the time director Mark Wilkinson was working with the teenage cancer unit at St James's Hospital in Leeds, where Beckie was being treated. He heard about the theft and offered to lend her his spare camera.

After seeing the powerful footage Beckie and her family were filming, and realising what an extraordinary young woman she was, he suggested they make a documentary. He worked closely with Beckie and her family for almost a year, following the ups and downs of coping with her inevitable decline.

Vicky says filming was hard at times

Filmed sitting on a beach in Bridlington one evening with her camera, she asks: "If there is a God up there, if you are up there, just please help us. You always seem to take the good people away and leave the bad people here. There's all these rapists and murderers about. There's no justice."

The diaries also show how the sisters faced the inevitability of Beckie's death, through humour - sometimes very dark humour - love and support.

The filming became a valuable distraction from the tension that built up within the family. They often picked up a camera and talked to it as if it was a close friend, resulting in an exceptionally intimate portrait of a family in emotional turmoil.

When Beckie died in late September 2004, Mark was invited to join the family for the last 18 hours of her life. Much of the time was spent watching her on video. As Vicky says in the film: "That's our Beckie on the video, that's not Beckie upstairs."

ONE life: To Courtney, with love was broadcast on BBC One, on Tuesday 24 May, at 2235BST.