A set of giant Olympic Rings has been unveiled at the entrance to the Channel Tunnel in France to mark 20/12 day. One of the world's most recognisable symbols, they will be seen by hundreds of thousands of fans who are travelling on Eurostar trains to St Pancras International. The unveiling coincides with 20/12 Day, a London 2012 Children's Promise scheme which provides children born in the UK on 20 December 2004 the opportunity to play a role in the Games.