The Jacobites were once a powerful political movement, dedicated to restoring the Stuart Dynasty to the thrones of England, Scotland and Ireland. The Stuarts had never been very good kings in the first place- their reigns tended to be marked by a unique combination of incompetence, tyranny and sheer bad luck- but they did have one advantage. Because they were descended from the ancient Gaelic royal house of Scotland (as well as a lot of other non-Gaelic royal houses), they had a certain appeal to the Gaelic clans of the Scottish Highlands. Those exact same clans had never shown any inclination to do what the Stuarts told them when they were actually in power, and the Stuarts for their part had always shown a pronounced dislike for their Gaelic subjects. But many of the clansmen sincerely believed that no one had the right to overthrow their lawful and ancient royal house, even if no one was really obligated to let it govern anything either.
The Stuarts managed to play into this abstract loyalty by repositioning themselves as protectors and defenders of the Gaelic way of life, which was a very compelling argument for a threatened culture like that of the Gaels. Many of the Highlanders managed to convince themselves that if the Stuarts regained the throne they would behave differently than any Stuart who had actually held the throne, and would restore the autonomy of their warrior society against the increasing threat of Anglicization and centralized government. Thus, the Highland loyalty to the Stuarts during the Civil War of the 1640s, and the Jacobite rebellions of 1688, 1715, 1719 and 1745.
Most people think the Jacobite cause was lost forever at the Battle of Culloden in 1746, or at least with the death of the last Stuart “pretender” (or person claiming to be the king) a few decades later. But there are diehards, and then there are diehards. Members of the “Royal Stuart Society” are modern Jacobites, who support monarchical government, oppose democracy, and consider the man in the picture above to be the legitimate heir to the British throne. This man is actually Franz, the Duke of Bavaria, but for complicated genealogical reasons he is believed by Jacobites to have inherited the Stuarts' claim. Why anyone would devote any mental effort to wishing that a Bavarian Duke held one powerless symbolic position instead of another is quite beyond me, but you have to admire their stick-to-it-iveness!