Author and 66-year-old socialite Lady C claims that Duncan shoved her while filming the final of the reality show's spin-off show, I'm A Celebrity...Get Me Out Of Here! NOW! on ITV2.
Lady C elaborated on the incident when grilled by Alan Carr on his Channel 4 chat show Chatty Man.
Alan: "How did you leave it with Duncan and Tony? Did you have a bust up with Duncan at the wrap party?"
Lady C: "No. He had a bust up with me, and not at the wrap party – live on television."
Alan: "What did he say to you?"
Lady C: "He didn't say anything. He was behind me, and the next thing I knew he pushed me out of the way and he was in front of me, raised his right foot and stamped on my left foot. It's there on television for all to see. Let's not speak about these tiresome old men. They are so tiresome and boring."
Earlier this week, Lady C had taken to Twitter, claiming Duncan had allegedly "physically assaulted" her on TV, and said: "Police came but haven't pressed charges."
Duncan denied such claims, saying he had no idea such altercation had even taken place. He tweeted in response to a Twitter user: "Of course not. I did not even know I had until it was mentioned on Twitter."
Duncan also denied that the police were involved, tweeting: "Police have told us that no such call was made."
Lady C clashed with Duncan and Tony Hadley in the jungle on numerous occasions. After leaving the jungle early on medical grounds, Lady C claimed that they tried to bully her in camp.
Both Duncan and Tony denied such claims, as did ITV, who said viewers were shown a "fair and accurate representation" of what goes on in camp, adding it was in fact Lady C "who resorted to name-calling and offensive remarks".
Chatty Man airs tonight (Friday 11 December) at 10pm on Channel 4.
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Who won in the jungle? See who was the last remaining celeb after three weeks Down Under: