Can you give us more info? History of the English Speaking peoples is a huge work in four volumes. What era are we talking about? Whom is he referring to as "prince?"

Britain had any number of principalities in which the ruler would be styled "prince" and not be the child of any reigning monarch.

http://en.wikipedia.org/wiki/Prince#Prince_as_generic_for_ruler

"Prince" can be a number of things:

• a generic term for a ruler (i.e. kings, dukes, counts...), as in Machiavelli's The Prince

• the head of state of a principality, as in the Principality of Monaco

• an aristocratic title not necessarily tied to lordship over a realm

• a label for a male heir or son in general of the ruling monarch

And some other variations and definitions sort of in between the above. Simply put, the word "prince" in English is not just the king's son.

The title prince is more exclusive in some countries and lot less so in other countries. Take Russia for example, sons of a king usually have a higher title of grand duke in English. People from other noble families not necessarily related to the royal family are often called prince/princess if they are ranked high enough. For example Felix Yussopov, who assassinated Rasputin, his official name is Prince Felix Felixovich Yusupov, Count Sumarokov-Elston, even though he is not not related to the Tsar by blood. In the book Anna Karenina the titular character and her brother are called princess and prince. (France, Holy Roman Empire, Spain, Netherlands, and Poland have similar titles for nobles.)

In addition to being the son of a king and being in high nobility, you can also be a prince if your family possess a territory historically or if you are the ruler of a smaller country (then you are essentially a king).

In England, it is common for most nobles to have many different titles that their family has amassed over the years. Typically they are referred to as just the greatest of these titles, but on certain occasions all titles might be recited, so they'll be called Duke of blah, Earl of bleh, Marquis of whatever, Lord of such and such. It is also customary for the eldest son and heir to be referred to, as a courtesy, by the second greatest of the titles the father has. So if someone is Duke of Denver and Earl of Margate, then his son might be referred to as Margate as a courtesy title. So, prince is technically 1) a title for a noble person who rules over a certain area of land, yet is beneath the King, who is head of state. And 2) prince can also be the title for the head of state of a princedom, also called principality. For example, Monaco is a principality and the ruler is Prince Albert. And 3) It's also a courtesy title not attached to any concrete properties, for younger sons of a ruler, such as prince Andrew and Prince Edward, younger bros. of Prince CHarles. When they got married, they each got actual lands and titles, rather than the courtesy titles they'd had. Prince Andrew became Duke of York, and is referred to as the Duke of York rather than Prince ANdrew, and that title is attached to properties. Prince Edward became Earl of Wessex, and he and his wife are referred to as the Wessexes in print. A kingdom has a king. A principality/princedom has a prince. A Grand Duchy has a Duke. Wales was a principality, but it was conquered by England, and so Prince of Wales became just one of the titles the King of England had. By tradition the title is awarded to the heir to the throne, kind of in the same way that it's a practice to call the son of the person holding the title, by the name of one of his lesser titles. But Prince of Wales is a concrete title with lands and taxes attached to it. Prince William is the heir to the heir to the throne, so he was called "Prince" as a courtesy, but did not have any principality attached to his name, it was just a title. So when he married, he became Duke of Cambridge, a concrete title he has in his own right.

"Prince" comes from the Latin "princeps," or "first." Augustus was the first to use the title ("first of the Senate"). It is NOT necessarily the heir to the throne, but can be a title of nobility in and of itself. For instance, there were a bunch of princes in the Holy Roman Empire. In the UK, the heir to the throne is traditionally given the title "Prince of Wales" (which is, in fact, a separate kingdom from England, just as Scotland is), but there's also the peculiarity of calling the young'uns in the royal family "princes" and "princesses," as courtesy titles—and not just in the UK, but other European monarchies, as well.