Words are inadequate

Wikipedia quotes the theory as:

In his book The Highland Clans, Iain Moncreiffe of that Ilk claimed that Elizabeth II of the United Kingdom "is the lawful Jacobite sovereign of this realm". Moncreiffe made the following argument:
... by the fourteenth century it had become common law (in both England and Scotland) that a person who was not born in the liegeance of the Sovereign, nor naturalised, could not have the capacity to succeed as an heir .... In Scotland, this law was modified in favour of the French from the sixteenth century, but was otherwise rigorously applied until the Whig Revolution of 1688, after which it was gradually done away with by the mid-nineteenth century. It was precisely because of this law that Queen Anne found it necessary to pass a special Act of Parliament naturalising all alien-born potential royal heirs under her Act of Settlement of the throne. But, of course, from the Jacobite point of view, no new statute could be passed after 1688 .... The nearest lawful heir of the Cardinal York in 1807 was, in fact, curiously enough, King George III himself, who had been born in England (and therefore in the technical liegance of James VIII).

The Wikipedia article then goes on to poke holes in this theory (unbiased my ass), but at least one historian has made that argument.