traditionally a Duke is ranked just below a king or queen, it is the highest peerage in the UK, that's why prince phillip is a Duke
rank of duke
duke
Duke of Edinburgh's Royal Regiment ended in 1994.
A royal designation is a title or rank given to a member of a royal family, usually indicating their position in the line of succession or their role within the monarchy. Examples include "King," "Queen," "Prince," "Princess," "Duke," etc.
An earl is a lower rank than a duke. A Duke is the highest rank of nobility right after the Prince. An Earl, on the other hand, is a lower rank above viscount and below a marquis.
a part of the royal family :royal uncle
A duke is sort of like a king but not as royal.
His Royal Highness the Duke of Cambridge
His Royal Highness the Duke of Cambridge
Duke of York - Prince Andrew
In terms of peerage, the highest ranking of the three is the duke, who is often a member of the royal family. The titles of earl and count share approximate rank, and are a couple of ranks behind the dukes. Normally, these would be considered lesser nobility.
His Royal Highness Prince William of Wales, Duke of Cambridge and Her Royal Highness Catherine, Duchess of Cambridge