"A huge contrast with Kate, who's very elegant and very dignified.
"Diana really warmed to people who were relaxed with her. Hopefully she could have got Kate to relax a bit more."
And according to Frank, one of the royal ladies is very similar to the late Diana.
"They don't have much in common except they married two brothers and have married in this role - this job," she explained, adding, that Megs is "very similar" to Lady Di.
"Meghan's a tour de force; she's all about the Meghan Markle brand. She's a very different person from Kate.
"Kate's a person who's careful and cautious; she's going to do things properly and slowly and think about them."