Bonnie Prince Charlie
Bonnie Prince Charlie, also known as Charles Edward Stuart and the Young Pretender, was the grandson of the former King James II of England and James VII of Scotland, who had been overthrown in the Glorious Revolution in November 1688.
Decades later, Bonnie Prince Charlie attempted to reclaim the English and Scottish thrones for his family in the Jacobite Rising which came to an end with the Jacobite defeat at the Battle of Culloden on 16 April 1746. Jamie McCrimmon witnessed the Prince fleeing from the site of the battle not long after it had ended.
The Prince gave Colin McLaren his standard to protect. The Second Doctor discovered this and appropriated it from the laird in order to convince Solicitor Grey that he was aware of the Prince's location and that they could split the reward money for his capture. The Doctor later claimed that Jamie was in fact the Prince in order to once again trick Grey. (DW: The Highlanders)
Alternative timeline
In an alternative timeline accidentally created by Jamie in 1688, the Glorious Revolution was a failure and James II remained on the throne until his death. Consequently, the Jacobite Risings and the Battle of Culloden never took place. His grandson Bonnie Prince Charlie eventually ascended the throne. He was still the reigning monarch in 1788. (CC: The Glorious Revolution)
Behind the scenes
In reality, Bonnie Prince Charlie died on January 31, 1788. This suggests that the frame story of CC: The Glorious Revolution may take place in January 1788. However, it is possible that he lived longer in the alternative timeline than in real history.