London, Sep 6 - Kelly Osbourne has promised her dad, rocker Ozzy Osbourne, that she won't get married until she has long, blonde hair.

Contactmusic.com reports that the 24-year-old, who is engaged to model Luke Worrall, recently dyed her locks blonde and has revealed that her makeover is part of a promise she made her father about her wedding day.

'There's a story behind the hair. My dad made me promise that when I got married, I'd have long blonde hair like I did when I was young. I spent three years growing my hair and dyed it blonde but it went a funny colour and all fell out. It's growing now, but I won't be getting married until it's much longer. After all, I promised my dad,' she said.

Kelly was thrilled when Luke popped the question on her last birthday, but admits she knew what he was planning.

'Because he's terrible at keeping secrets, I knew he'd bought me a ring so I had a little time to prepare myself - after all, it's a really serious decision. I knew he was my soul mate from our first week together - I've never laughed that much in my life,' she said.