After winning a silver and bronze medal in the London 2012 Olympics, he said being chosen for the honour was the proudest moment of his life.
Following the Olympics, Smith won BBC dance series Strictly Come Dancing.
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Theresa May has welcomed passage of her flagship EU Withdrawal Bill through Parliament.
It comes after a report found more than 450 patients had their lives shortened after being prescribed powerful painkillers.
“We’re going to keep families together and the border is going to be just as tough as it’s been,” the president told the crowd.