It refers to the establishment of a group of influential and fashionable people who would gather around a family "opponent" of the King. It was prominent among the Georgians with George, Prince of Wales, heir to King George I setting up his own Court as a rival to that of his father, the dislike even hatred between them was mutual. 

It continued when he became King George II and his heir, Frederick, Prince of Wales (who died before his father, thus was never King) and was perpetuated further with George III (Frederick's son) and his son George, Prince of Wales (later Prince Regent and then King George IV).

It was the younger Princes who invariably attracted the most brilliant men and women thus the enmity between father and son only grew.    

The novel Queen in Waiting by Jean Plaidy is a good telling of the rivalry between George I and his son where the "tradition" first began.   

I'm getting flashbacks of a future play that never gets produced with Charles, Earl Spencer as Richard Neville, Prince Harry as George, Duke of Clarence and Meghan Markle as Margaret of Anjou.

But seriously, I did a little research on the very impressive Spencer family.  I think the Germans did considerable damage when they came to the throne as far as understanding how the system worked and a seeming lack of interest in learning.  From my limited point of view, there isn't much to admire from George I until William IV.  Of course, you know which side of the Atlantic I stand as regards George III.  As it seems to happen with the British Monarchy, it took a woman with tri-fecta strength (queen, wife, mother) like Victoria to bring the family in line.  (I refer to an earlier Eleanor of Aquitaine quote.)  It's current strong women will keep it that way.

The downfall of a Spencer Rival Court will come from within.  It will become the Sparkle Rival Court because drama and chaos follow Harry and Meghan and Meghan clearly demands control.  I think she will find the Spencer women are every bit as strong as the Mountbatten-Windsor women.

I have probably read Jean Plaidy's book.  She and as Phillipa Carr was a reading phase once upon a time.

I've got two books on the US rigid airships published by the US Naval Institute Press, Annapolis. 

I'm getting flashbacks of a future play that never gets produced with Charles, Earl Spencer as Richard Neville, Prince Harry as George, Duke of Clarence and Meghan Markle as Margaret of Anjou.

But seriously, I did a little research on the very impressive Spencer family.  I think the Germans did considerable damage when they came to the throne as far as understanding how the system worked and a seeming lack of interest in learning.  From my limited point of view, there isn't much to admire from George I until William IV.  Of course, you know which side of the Atlantic I stand as regards George III.  As it seems to happen with the British Monarchy, it took a woman with tri-fecta strength (queen, wife, mother) like Victoria to bring the family in line.  (I refer to an earlier Eleanor of Aquitaine quote.)  It's current strong women will keep it that way.

The downfall of a Spencer Rival Court will come from within.  It will become the Sparkle Rival Court because drama and chaos follow Harry and Meghan and Meghan clearly demands control.  I think she will find the Spencer women are every bit as strong as the Mountbatten-Windsor women.

I have probably read Jean Plaidy's book.  She and as Phillipa Carr was a reading phase once upon a time.

There's very little to recommend George I. But George II and III had certain qualities of being loyal to their adopted country, George III in particular even though he never travelled beyond the English Midlands in his entire life. George IV was the first to begin the practice of the Monarch actually travelling around the Kingdom for reasons other than pleasure. He was the first to go to Scotland in 170 years and Ireland in 130 years.  

George II doesn't come across as overly decadent to me beyond a mistress or two. George IV is the one for true decadence. Hanoverian family relations were always strained. It was the behaviour of George III's brothers that compelled the King to organize the Royal Marriages Act in 1772 so that his sons wouldn't damage the succession with unsuitable wives.  

Colombus sailed to the New World three times yet never actually landed on the mainland of the Americas. All his landfalls were made on the Caribbean islands. The Vikings were the first to land in North America around 990, the first in South America were members of Amerigo Vespucci's expedition in 1499.   

All part of the modernization of the Monarchy, allowing them to marry commoners of their own choosing.