1314

In 1314, Thomas Randolph fought the English in Edinburgh, successfully retaking Edinburgh Castle for the Scottish. (PROSE: The Many Hands)

Behind the scenes
In Renaissance of the Daleks Nyssa says she was in Rhodes in 1320, while the Doctor later says it was 1310. Given the Doctor has a better knowledge of Earth's history than Nyssa, and the fact the real life Knights Hospitaller took over Rhodes in 1310, as is depicted, 1310 is the most likely date for this to be set.