Father and son were guests on ITV's Lorraine, where Duffy Senior said: "I know he's very eager to do well. "I'd love to be able to show him any areas that he might be going wrong in.
"I've been looking for those areas, and to be honest I haven't been able to find any!
"Anything he's done, he's done very, very well. He's very natural and he doesn't need my help at all."
His son said: "If there was ever a scene that I wasn't so sure about - the emotions going on or whatever, I'd always ask him - because obviously he'd be a lot more educated on it than me.
"It's always great to have him there. He lets me do my own thing, though, so it's great."