A helium balloon bought to celebrate a special occasion will usually deflate within a couple of weeks.

But for A-level student Zachary Starr, the decoration purchased at Kent and Canterbury Hospital to mark his birth 18 years ago is still going strong.

The King’s School pupil, of St Vincent’s Close, Littlebourne, posed with the balloon ahead of his landmark birthday tomorrow.

His mum Louise Preece, who runs an electrical engineering firm, says she is shocked the balloon is still inflated.

“They usually disappear within a fortnight but it is still there,” she said.

“It is exactly the same size as when it was blown up – it was one of the small ones you can buy and it just has not changed.

“It is a bit tatty now, but we have always kept it and we are going to leave it and see how long it lasts.”