By Mark Simpson BBC North of England correspondent

Sally was given little chance of making her seventh birthday Sally's birthday

Yorkshire schoolgirl Sally Slater was minutes from death as she waited for a heart transplant operation six years ago.

Her struggle for life touched the nation. Now, with a 55-year-old heart, she's celebrating her 13th birthday.

She now leads such an active life that it is difficult to keep up with heart-transplant girl Sally Slater.

When I phoned her dad on Monday, he told me: "Sorry, she's on a school trip."

So could I talk to her when she got home?

"Fine, as long as you don't mind waiting 'til Friday as she's not back 'til then."

Come Friday afternoon, she was celebrating her 13th birthday by jumping for joy - literally - on a trampoline in her back garden.

Sudden hope

Six years ago, the only trips Sally was going on, were in and out of the operating theatre at Freeman Hospital in Newcastle-upon-Tyne.

The only sport I'm not allowed to play is rugby. Which doesn't really bother me! Sally Slater

The little girl had been struck down with a mystery virus which was killing her. Sally had cardiomyopathy, and desperately needed a new heart. At the time, she was looking forward to her seventh birthday but was given little chance of making it.

Auto-immune diseases are caused when the immune system, for some reason, decides that a certain type of the body's own cells are foreign and starts attacking them.

A picture of Sally's tiny body lying on a hospital bed, clutching her favourite soft toy, was printed in national newspapers as doctors waited for a donor heart.

After a 10-day wait, and with only minutes to spare, one became available. For her parents Jon and Bridget - who had gone through the anguish of saying goodbye to their six-year-old daughter - suddenly there was hope.

Their gain was of course someone else's loss. The grieving family of a 49-year-old woman from the North-East - her name has never been revealed - agreed to donate the heart after seeing the image of Sally lying in her hospital bed.

Within three months of the operation she was allowed home, and since then has made a remarkable recovery.

'Saves lives'

She and her family live in the Yorkshire Dales, in the village of Kirkby Malham, near Skipton.

Sally, clutching her favourite soft toy, in hospital six years ago

Sally goes to Settle Middle School, and enjoys playing the piano, acting and skiing. Her ambition is to become a primary school teacher.

She has to take six tablets a day - to guard against infection and organ rejection - and she must go for a hospital check-up every three months.

Given that her heart is 55 years old, she may well need another operation, but says she isn't scared.

Ask her how she feels, and she says succinctly: "Very well, thank you."

"Totally normal?"

"Yes. The only sport I'm not allowed to play is rugby. Which doesn't really bother me!"

She remembers little about her near-death experience, but needless to say she is a passionate believer in organ-donation.