First of all, the accession of James VI of Scotland to the English throne did not bring about the union of the two kingdoms. That happened in 1707 when parliament passed the Acts of Union, more than a century after the union of the crowns. James wanted to unite the kingdoms but was thwarted in parliament. To put it mildly, the English gentry looked down on the Scots and didn’t want them placed on equal footing. For their own part, while desiring equal status, the Scots valued their independence. A move by James’ son Charles I in 1637 to unite the English and Scottish churches (through the imposition on Scotland of a Book of Common Prayer based on the English version) set off a rebellion in Scotland which ultimately led to the English Civil Wars.

In the case of William of Orange, there were not even two crowns to unite. The Dutch Republic was not a monarchy. Before his accession to the English throne alongside Mary II, William had not been a King. His position as a Dutch Stadtholder was, by contested tradition, hereditary, in that a strong political faction supported such inheritance. He was in-effect head of state, but this was not quite equivalent to a crown. His was largely a position of diplomatic and military command (his greatest strengths), and it was in military matters that the most significant union existed between the English and Dutch. William’s whole purpose was to resist the territorial ambitions of Louis XIV while championing the protestant cause on the Continent. To this end he saw England more as a military asset than a people to rule. The reality of Dutch hegemony in military affairs was resented by the English, beginning with Williams arrival into a London taken over by Dutch infantry (he wanted to be seen as a liberator instead of an invader, but didn’t trust the English to keep the peace). Despite many cultural and economic similarities, there were not a lot of warm feelings between the two countries as both vied for position and power in Europe and overseas. They had fought each other in three wars during the 17th century, the most recent one ending only 15 years before William’s accession, and would fight again in the 18th. The countries were ‘united’ in their administration and military institutions, but on neither side was there much desire for political union.

William was never a popular king, preferring the company of his Dutch generals to English statesmen and society. His arrival in England was generally welcomed, as he provided the military muscle to see off the Catholic James II, but it was Mary they really wanted. Before her early death it was she and not William who most often performed the constitutional role of Monarch as William tended to his wars. Prior to the birth of James II’s son, it had been assumed that Mary would inherit and William would come as part of the package, but had he not been directly invited to invade he may not have been in a position to demand an equal royal title to his wife’s. As it was, he refused to be his “wife’s butler” and threatened to take his toys and go home if not given a crown, leaving England to a return of James, so the two monarchs ruled jointly. This being decided by act of parliament, it established parliamentary supremacy in the English state. William and Mary never had children, so on William’s death the English crown went back to the Stuart line with Mary II’s sister Anne. There was no Orangist dynasty in England. Under Anne, however, union with Scotland finally happened.