Simon Cowell used an aerial sign writer to wish Cheryl Cole a happy birthday.

'The X Factor' boss hired five planes to emit a computer-controlled and eco-friendly vapour that spelled out a message from a height of 10,000ft in the sky.

The over-the-top display took place in Las Vegas, Nevada where the Girls Aloud singer was celebrating her 29th birthday with bandmates Nicola Roberts and Kimberley Walsh.

The message over the city's Encore hotel read: ''Cheryl - Congratulations you're 30 next year! ha ha ha Love Simon x.''

The writing could be seen from a 15-mile radius.

The music mogul has been waiting since October to get revenge on Cheryl after she reminded him of his age.

She sent a plane to fly around his house in Los Angeles 52 times with a banner attached saying: ''Simon Cowell is 52 today! Ha ha ha! Love Cheryl xoxo.''

She explained at the time: ''He didn't want anyone to know it was his birthday. A perfect opportunity for me.''