Kaylee Davidson, who doctors said would never see her fifth birthday, celebrated 21 years since becoming Britain’s youngest successful heart transplant baby.

Davidson is doing so well, she’s now training to compete in next year’s World Transplant Games in Australia.

Kaylee, born in April 1987, was diagnosed when she was just four months old with an incurable disease known as cardiomyopathy.

It’s a condition in which the heart muscle becomes inflamed and doesn’t work as well as it should.

At the time of the pioneering transplant, only two children in Britain had received new hearts — and both had died.

Kaylee, now a sales assistant, said she will never forget her donor.

“That baby is keeping me alive — but I’m keeping her alive. We’re a team.”

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