When the current King Charles III ceases to be monarch, the title Prince of Wales will cease to exist for William. Upon his accession, the 43-year-old heir will immediately assume the highest rank in the British peerage, becoming King William V, or simply King William. This fundamental shift marks the end of a role he has held for over two decades and the beginning of his new identity as the sovereign head of state.
The Title He Leaves Behind: Prince of Wales
The title Prince of Wales has been synonymous with William for 24 years, ever since Charles bestowed it upon him in 2022. Unlike a surname, this is a substantive title traditionally granted to the heir apparent. For centuries, it has served as the primary designation for the man next in line, carrying with it significant public duties and a distinct public identity. When William becomes king, this title will be retired, as it cannot be held by the reigning monarch.
Historical Precedent and the Last Transition
Looking to history provides the clearest guide for William's future title. His grandfather, Prince Philip, Duke of Edinburgh, held a specific title before his wife, Queen Elizabeth II, ascended the throne. Upon her accession, Philip did not become King but was created Prince Consort, a title he held until his death. More directly, William's father, King Charles III, was known as the Prince of Wales for 64 years before becoming king. When Charles became king in 2022, the title was immediately vacated, establishing the precedent that the heir's title is surrendered upon accession.
The Sovereign's Style: King William V
The formal title for the British monarch is "King of the United Kingdom and the other Commonwealth realms." While the regnal number is used for distinction, the common form of address is simply the regnal name. Therefore, William will be universally known as King William. His official regnal number will likely be V, following the historical William I (the Conqueror) through to William IV in the 19th century. This is the name that will appear on currency, stamps, and official documents, marking the start of his reign.
Addressing the Monarch
As king, the form of address will change significantly. Instead of "Your Royal Highness," William will be addressed as "Your Majesty" at all times. This is the standard, formal mode of address for a sovereign. The public and media will also likely refer to him as "His Majesty King William" or simply "the King," reflecting the supreme position he holds within the constitutional structure of the United Kingdom.
The Queen Consort Distinction
Unlike his father, whose wife became Queen Camilla, William's wife, Catherine, will automatically become Queen Consort upon his accession. She will be addressed as Queen Catherine, a title distinct from the sovereign's role. This creates a clear distinction within the royal household: King William as the reigning monarch and Queen Catherine as his consort. Her title is derived from his position, not held independently, reinforcing the constitutional framework of the monarchy.
Speculation on a Duke Title
It is widely expected that, following the pattern set by his father and other recent monarchs, William will be granted a hereditary peerage upon his accession. While he is already the Duke of Cambridge, a new, perhaps more senior title is likely in the mix. Historically, princes who are already dukes are elevated to different peerages upon becoming king. Speculation often falls on titles such as Duke of Lancaster, a title held by the sovereign that represents the king's estates in the historic county, or potentially a new creation that solidifies his lineage and separates his ducal roles from his royal duties.
