Speaking to Yahoo's Royal Box, Frank said: “Harry is a Virgo, and they love to do things for other people.
“They actually make quite a good couple in a way, it is earth and fire.
“He is a bit more like the royal servant, even though he is the royal prince.
“But, he would just love to just do everything he can for her, he is very devoted.”
Prince Harry and Meghan Markle are expecting their first child together in late April or early May this year.