text: Kate McCann set off from Edinburgh on Saturday morning with about 20 other cyclists.
  The five-day challenge is in aid of the Missing People charity.
  It will pass through Newcastle, York, Nottingham and Northampton before crossing the finish line in London on Wednesday.
  Mrs McCann is an ambassador for Missing People and last year launched Child Rescue Alert, which has seen more than 250,000 people sign up to receive alerts when a child is feared to have been abducted.
  Her daughter Madeleine was three when she went missing from the family's holiday apartment in Portugal's Algarve on 3 May 2007.
  The case has become one of the most famous missing persons cases of all time.
  Mrs McCann said: "The night that our little girl was taken from her bed, we mistakenly presumed that an alert would have gone out immediately to the public to get as many eyes and ears involved in the search as possible.
  "But no such system existed to get a message out into the public domain quickly and recruit help.
  "Although a simple idea, Child Rescue Alert is a potentially life-saving system, the success of which is reliant on us, as members of the public, to sign up to receive free alerts when a child goes missing.
  Mrs McCann launched the child rescue alert scheme with the mother of murdered schoolgirl April Jones last year.
  The scheme is designed to use social media, text messages, email and digital billboards across the UK in addition to traditional broadcast media to issue alerts.
target: The mother of Madeleine McCann has embarked on a 500-mile (800km) charity bike ride to raise funds to support families with a missing loved one.