You mean William, he'd be the heir apparent after Charles. Though I'm probably missing some historical sublety here.
In the late 17th century, King James II sought to rule all the Kingdoms of the British Isles as one United Kingdom; which caused rebellions from Scotland to England, both of which were crushed. The English were especially chafing under this monarch who flitted between religious toleration and Catholic assertion, who sought to rule as a Scottish King against an English parliament, curtailing the power of the parliament tremendously, making James II one of the most powerful monarchs in English history. King James II probably could have ruled until death had he not got his wife pregnant, which caused Protestants in Britain and Netherlands to increase their plotting to a frenetic level of energy. For the Westminster parliament, a definite catholic line of succession would spell the deathknell for their parliamentary power in favour of Royal rule, but for the Dutch this was absolutely worse case scenario. King Louis XIV of France had been expanding all over Europe, with three principle opponents: England, the United Provinces (Netherlands) and the Holy Roman Emperor, Emperor Leopold I.
Emperor Leopold I was preoccupied with fending off the great kebabini Empire (it had only been a few years since
the siege of Vienna), thus the Emperor's support against France was uncertain. The Dutch were at this point a redonkulously stronk naval power, and while the Dutch could not defeat the French army, they could open their dykes and flood the Netherlands, grinding the French campaign to a halt. Consequently the French realized that in order to defeat the growing alliance of Italian, Dutch, German and Spanish states they needed an alliance with the English to neutralize their Dutch flanks, giving the English french monies in exchange for alliance. This made it all a very dangerous position for the Dutch, and so they planned to launch a military regime change in England, to depose the French-friendly Catholic monarch and replace him with a Dutch friendly protestant one. Before the Dutch can complete their invasion plans, William of Orange, the Stadtholder of the United Provinces, receives an invitation from English bishops, politicians (from both Tory and Whig parties) and commanders, to come to England and claim the throne himself.
The Dutch invaded, commanded by William the Most Highest Orangest. This is notable for being the last successful invasion of the British Isles in history; the Dutch forces were disciplined, looting nothing, working closely with their English allies to defeat James's less experienced forces (by contrast, the Dutch forces were veterans of many wars). The Dutch gained a powerful ally against the French (unfortunately for the Netherlands, the English would prove to be vastly more dangerous as allies than enemies), the English re-established the sovereignty of Parliament, revoking the ability for the Monarch to dispense laws or create armies in peacetime, entrenching parliamentary practice to this day. What is probably most remarkable is that the casualties incurred in the Dutch invasion were like 2 dozen dudes. It would also cause some severe shitflinging a century later, when French revolutionaries and their allies argued with British conservatives and their allies, with the Irish statesman saying the British had the Glorious Revolution, while the French had a fake news Revolution; Thomas Paine, the Anglo-American disagreed, saying the Glorious Revolution was the fake news Revolution. The rest would be bloody wars and that dickhead Napoleon slaughtering gorillions of people in the name of freedom, the first recorded instance of freedoming people into the liberty of death, only by bayonet instead of bomb.
But that's getting off topic, basically martinuzz is saying the Dutch will invade London, kick Theresa May out of no.10 and replace her with a Dutch sausage vendor