I'm not sure the next in the line of succession automatically becomes the Regent, they have to be appointed so for all we know steps may have been made to ensure it's not harry
Everyone one is dead was the speculation.
Requirements :
Act of Settlement 1701-he's passing .
Regency act 1937,1953
Passing the requirements:
over the age of 21
a British subject domiciled in the United Kingdom
capable of succeeding to the Crown under the terms of Act of Settlement 1701
'' According to the Regency Acts in force, if the monarch is under the age of 18 years when he or she succeeds to the throne,
a regency is automatically established, and, until the monarch attains the age of 18 years, the royal functions are discharged by the regent in the name and on behalf of the monarch ''
The temporary version which requires the involvement of:
the wife or husband of the Sovereign
the Lord Chancellor
the Speaker of the House of Commons
the Lord Chief Justice of England
the Master of the Rolls
is about the Monarch's '' infirmity of mind or body, '' not that everyone is dead like our hypothetical case.
Which was a reflection on ''security,'