Kate McCann has been announced as an ambassador of Missing People and launches the biggest digital billboard campaign in British history today, with over a £1m of ad space.

A network of billboards across the UK will include details of missing individuals, raising awareness of a new number to call for sightings and encouraging the public to join the search. It's the first public role Kate has undertaken since her daughter Madeleine vanished days before her fourth birthday in Praia da Luz, Portugal, in May 2007.