British Olympic champion Andrew 'Bart' Simpson, who won a gold medal at the 2008 games and a silver in 2012, has died after his yacht capsized off the California coast during training for the America's Cup race.
Sir Keith Mills, the deputy chairman of Locog (London Organising Committee of the Olympic and Paralympic Games) was due to be made a Knight Grand Cross - the highest grade of knighthood.
A London 2012 spokesman said: "We are all deeply saddened by the news of Andrew's death and, as a result of this tragic accident, Sir Keith will no longer be attending his investiture at Buckingham Palace today."
This footage from the America's Cup official website illustrates just how challenging it can be to sail the boats taking part in the America's Cup series. It's the oldest sporting event in the world, having taking place off the Isle of Wight for the first time in 1851.
The type of craft Andrew Simpson was sailing on is the new AC72 super catamaran. It is 72 feet long and powered by a huge wingsail. This design of yachts are contesting the America's Cup for the first time. They are faster and harder to sail than the monohulls used in previous contests.
The catamarans needly a highly skilled sailing team to keep the power under control. In the choppy waters of San Francisco bay the crew have to try to stop the catamaran's pitch-polling. This happens when the bow digs into a wave and the yachts tip over.
Former America's Cup sailor Andy Green has said that Andrew Simpson was questioning whether he wanted to continue sailing.
Speaking to BBC Radio 4's Today programme, Green said: "He was questioning whether he wanted to continue sailing, but because his friend Iain Percy was at Artemis he went over there in February and started racing with them as a valuable asset.
"He will be sorely missed by them.
"It's particularly poignant for a British audience that this tragedy has happened because of his history in the Olympics, but I can only hope that Britain goes on to get involved in the America's Cup and win it back, with this very firmly in mind."
Paul Cayard, CEO of Artemis Racing, said at a press conference: "We obviously had a tragic day today on the bay. Our thoughts and prayers are with Andrew Simpson's family - his wife and kids, and also with the rest of the team mates. It was a shocking experience to go through."
San Francisco Fire Department spokeswoman Mindy Talmadge confirmed to Press Association Sport that Andrew 'Bart' Simpson was taken to St Francis Yacht Club on the shore where paramedics performed emergency resuscitation, but he was pronounced dead.