There's no such contract. However, in the constitution for orders it basically says that the medals belong to the crown, so that's very clear to everyone. In terms of medals and decorations, it has always been, from our very early roots when we received medals from Britain, that declarations and medals presented to you were your personal property. But no one has ever been asked to sign a piece of paper, other than saying they received the medal. That's about it.
On October 21st, 2010. See this statement in context.