Until 1937 no permanent statutory provision had been made either for a regency in the event of the Sovereign being incapable of personally performing the royal functions or for the delegating of such functions during temporary absence or illness.
Following the Abdication of King Edward VIII in 1936 and the Accession of King George VI, Princess Elizabeth was Heiress Presumptive however she was under the age of eighteen. There was a desperate need for a Regency Act. Parliament passed the Regency Act 1937 which provided for the incapacity or minority of all future Monarch and established in statute the office of Counsellor of State – standing in for the Monarch while they were overseas or with temporary incapacity.
The Act required that the Regent, if needed, should be the next person in the Line of Succession, be over the age of 21 and capable of succeeding the Crown under the terms of the 1701 Act of Settlement. Counsellors of State could be the consort of the monarch or the next four people in the Line of Succession over the age of 21.
When the Act was passed in 1937, Prince Henry, Duke of Gloucester would have become Regent if King George VI had died before Princess Elizabeth turned 18.
In 1943, there was a slight modification of this Act which stated that the heir apparent or presumptive only had to be 18 to become a Counsellor of State.
The 1953 Regency Act was passed the year after Queen Elizabeth II ascended the throne. The Queen’s heir, Prince Charles, was still a minor and under the Regency Act 1937, Princess Margaret would’ve become Regent had Her Majesty The Queen died. The new Act, which ceased to have any relevance in law once Queen Elizabeth and Prince Philip’s children all reached the age of 18, stated that if still living, Prince Philip, would act as Regent in case of an underage succession to the Crown by one of his and The Queen’s children.
David Maxwell-Fyfe, Home Secretary at the time, said at the Bill’s second reading, “The Amendment is confined to the Duke, and accordingly, in the event of the Duke’s death, which we all fervently hope will not occur for many years, the Amendment would cease to have effect, and in the circumstances in which provision is made by the Bill for the Duke being the Regent, the Princess Margaret would, if alive, be Regent. This is in no sense an exclusion Bill.”
The Regency Act 1953 also allowed The Queen’s mother, Queen Elizabeth The Queen Mother, to become a Counsellor of State, a position she had lost upon the death of her husband.