Prince of Prospect
Prince of Prospect (or Princess of Prospect, if female) is the term used for the first person in the line of succession to the Talossan throne eligible to serve as King.
The current Prince of Prospect is Patrick, followed in succession by Peter. To be eligible to the throne, a person must be a citizen of Talossa, which is the reason why Andrew Woolley, eldest son of the King and not a citizen of Talossa, is not the Prince of Prospect. Patrick's claim to first succession makes him heir presumptive and therefore Prince of Prospect, but should Andrew Woolley become a Talossan citizen, he would displace Patrick and become (without any way for his own place to be overtaken) heir apparent and Prince of Prospect.
In this term, "Prospect" does not specifically refer to Prospect Avenue, the important street that runs through the nation of Talossa, although it can be said that the street was named for the Talossan heir presumptive.