What should be Prince William's regnal name?

[Suburbia]

What should be Prince William, Duke of Cambridge's regnal name when he steps to the British throne?

His full Christian name is William Arthur Philip Louis. Should he go with Arthur, probably named after King Arthur. Philip, named after his father Charles (Charles's middle name), and Philip, his grandfather.

Louis, probably after his great-great-uncle. 

William the Fifth (William V) is the the most likely name.

[Lechasseur]

William V

[Kingpoleon]

William V - the really interesting question is, if William and his heirs were stricken from the line of succession or all died before becoming King, would Prince Harry become Henry IV or Charles III?

[Zioneer]

William V, probably.

But for the record, I'm disappointed that Prince George is named George and not a more unique name, I think having a new regnal name would be interesting.

[H.E. VOLODYMYR ZELENKSYY]

William V - the really interesting question is, if William and his heirs were stricken from the line of succession or all died before becoming King, would Prince Harry become Henry IV or Charles III?

Don't you mean Henry IX?

[mvd10]

Willem Alexander

[True Federalist (진정한 연방 주의자)]

I'll hope for the improbable but possible Philip III.

[AndyHogan14]

William V - the really interesting question is, if William and his heirs were stricken from the line of succession or all died before becoming King, would Prince Harry become Henry IV or Charles III?

Harry would not inherit the throne immediately if William died, he is fifth in line to the throne behind Charles, William, George, and Charlotte. If William were to die before he accedes to the throne, George and Charlotte would retain their position ahead of Harry.

That said, I always assumed William would just be William V and Prince George, George VII, the big question is what Charles' regnal name will be. He could be Charles III, but that name does not have a very good history...his full name is Charles Philip Arthur George, and I don't see him taking Philip or Arthur (no one should take the name Arthur), so George VII it is (pushing Prince George back to George VIII).