Sian Williams has quit the BBC to take over as the main host of Channel 5 News.

Sian Williams

Sian Williams

The 50-year-old broadcaster is set to replace Emma Crosby - who is pregnant with her first child - as the face of its flagship evening news programme '5 News at 5' after 30 years at the BBC.

Sian - who will begin in her new role in the New Year - said: "I've always admired ITN's approach to news and 5 News' output, both domestic and international, is consistently high quality and accessible. With Channel 5 pledging to boost its coverage even further, it's a terrific opportunity and an exciting challenge to join this talented and impressive team."

Sian - who currently presents the weekly BBC One programme 'Sunday Morning Live ' - anchored 'BBC Breakfast' fore more than ten years, has presented all the main 'BBC One News' bulletins and continues to make documentaries for BBC Radio 4.

She's also hosted BBC programmes 'Crimewatch', 'Goodnight Britain' and 'National Treasures Live' and been involved in the coverage of events including the London Olympics and the Royal wedding of the Duke and Duchess of Cambridge.

Emma took to her Twitter account to reveal she was leaving Channel 5 news this morning (05.11.15) ahead of the announcement.

She wrote: "Some of you may have spotted my expanding belly, I'm off to have a baby! Tomorrow is my last day on @5_News. Thanks for a brilliant 5 years. (sic)"