Meghan, Duchess of Sussex, has been told to "grow up" by her father

Speaking on 'Good Morning Britain', Thomas said: "I don't know what changed her. She's never been that way before and once she hooked up with Harry, she changed.

"I understand that she hooked up with Soho Club and a different group of people, but she's pretty much disowned both sides of her family, and I don't understand the reason...

"We're at a point where, I think, both of us, we should grow up, talk, make up for the sake of the children right now and for ourselves. This is ridiculous, it's being going on for almost four years - it's crazy."

And Thomas claimed his daughter gave him an ultimatum to cut contact with her estranged stepsiblings, Samantha and Thomas Jr..

He said: "There are some reasons that she got upset with me and one was that she thought I was giving too much attention to her brother and sister - to her stepbrother and stepsister - but nonetheless she wanted me to stop talking to them and I couldn't."

Although Meghan and Harry - who have children Archie, two, and Lili, four months, together - are now living in California, Thomas won't risk trying to see them in person in case he's portrayed as a "stalker".

Asked by host Susanna Reid when he last tried to get in touch with his daughter, he said: "About a month ago maybe. I really can't go down to Montecito because I'll be pointed out as a stalker, so I can't do much like that.

"'But my message for the kids is that they have two loving families and their great-grandmother is the Queen of England, and I think that that's important for them to know.

"It's important for them to know that they have two families, and eventually they're going to grow up and they're going to want to know more about them, so we'll see what happens."