It might be very much in the ‘just in case’ corner but The Regency Act 1937 is a powerful document that decides who controls the Crown if the Monarch is either unable to carry out their duties or if the throne passes to a child. And the Act that sets the stall out in the 21st century is rather different from previous provisions. For until the early 20th century, it was presumed that if a royal under the age of 18 needed a regent, mother always knew best.
There were no general laws around regencies until the early 1700s with monarchs deciding who controlled the Crown if they were absent or if a child should inherit the throne. As Parliament’s power grew, that began to change. The House of Hanover saw a string of acts around regencies passed.
King George II was determined to leave his wife in charge when he had to head back to Hanover and so the Regency During the King’s Absence Act 1728 appeared, putting power in the hands of the rather popular Queen Caroline. Her death, in 1737, did nothing to ease the rift between her husband and their eldest son but when Frederick, Prince of Wales died in 1751, George faced an even greater problem. The heir to the throne was now Frederick’s twelve year old son, George. The  Minority of Successor to Crown Act 1751 quickly came into being, allowing George’s mother, Augusta, to rule should he take the throne before the age of 18.
In fact, the prince in question didn’t become King George III for another nine years but his marriage soon after his accession led to another consideration of regency laws. George and his wife, Charlotte, quickly welcomed a growing family and by 1765 they had three young children, leading to the Minority of Heir to the Crown Act 1765 being passed. Charlotte was named as a regent alongside Augusta.
They were never called on to rule although two more Regency Acts were passed during George III’s reign owing to his mental health issues. Both put his eldest son, the future George IV, in charge. The next act to cover the rule of a minor was passed in 1830 when George IV died and was succeeded by his younger brother, William IV. William had no surviving legitimate children and his heir was his eleven year old niece, Victoria. The Regency Act of 1830 stipulated that her mother, Victoria, Duchess of Kent, would rule for her should she succeed before the age of 18. William IV famously hated his sister in law so much, he vowed to live long enough to stop her being regent and was as good as his word. He died on June 20th 1837, a month after Victoria turned 18.
The new queen famously married her cousin, Albert, in 1840 and soon had a stable of heirs of her very own. Having missed out on giving her beloved husband the title of king, Victoria ensured he was named regent in the Act passed in 1840 as they welcomed their first child.
In 1910, the issue of an underage monarch arose again when George V took the throne. At the time, his heir, Edward, was approaching his 16th birthday. The 1910 Regency Act named George’s wife, Queen Mary, as regent in the event of the throne passing to a minor.
It was only in 1937 that the idea of making the Monarch’s mother regent took second place to practicalities. The current rules align the Regency with the Succession so if a royal under the age of 18 inherits the throne, the next adult (aged 21 or more) in the line of succession becomes regent. If they are unable to take on the role, all eyes move along to the adult after them. The mother of the monarch isn’t named anywhere although they retain guardianship of their child until they turn 18.
It’s a very different way of managing the Monarchy than in times past and has been in place for almost 85 years. Currently, the first person in the line of succession who could succeed to the throne under the age of 18 is Prince George. As things stand, his regent would be his uncle, The Duke of Sussex.