Deputy Prime Minister Nick Clegg tweeted:
Our thoughts tonight are with the people of South Africa. Nelson Mandela's legacy will continue to burn brightly around the globe.
Six-year-old Emma Williams was invited to sit on Nelson Mandela's lap when he visited Wales in June 1998. Now 22, she speaks to ITV News.
Nelson Mandela touched aspects of British public life in a way that very few other international figures have managed.