Bishop Asser tells the story of how as a child Alfred [the Great of England] won as a prize a book of Saxon poems, offered by his mother to the first of her children able to memorize it.
Following the example of Charlemagne, Alfred [the Great of England] established a court school for the education of his own children, those of the nobility, and "a good many of lesser birth". There they studied books in both English and Latin and "devoted themselves to writing, to such an extent .... they were seen to be devoted and intelligent students of the liberal arts".
Charlemagne instituted schools to educate members of the nobility.
Charlemagne's native language was probably Old High German.
He also spoke Latin and understood Greek, according to Einhard (Grecam vero melius intellegere quam pronuntiare poterat, "he could understand Greek better than he could speak it").
there is a story that he practiced writing but keep his writings hidden under his pillow because of embaressment at his poor style.
Chilperic I c. 539-584 was a Frankish king with some degree of culture.
Yet, he was also a man of culture: he was a musician of some talent, and he wrote verse (modelled on that of Sedulius); he attempted to reform the Frankish alphabet; and he worked to reduce the worst effects of Salic law upon women.
I believe Chilperic introduced three new letters to the alphabet that were abolished after his death.
Emperor Frederick II (1194-1250) wrote De arte venandi cum avibus about hunting with falcons.
Conradin (1252-1268) was said to be "beautiful as Absalom, and spoke good Latin".
I believe that William of Norwich (1132-1144) was said to have been taught to read and write (English or Latin?) by his parents. So the author of his biography considered it plausible for ordinary townspeople to have some education - though perhaps not knowledge of Latin.
Any way these example show that Latin speaking and/or literacy as not limited to priests but at least some secular leaders knew Latin.
Added 05-15-2017. According to Dominic Mancini King Edward V (1470-1483?) as literate in at least one language.
In word and deed he gave so many proofs of his liberal education, of polite nay rather scholarly, attainments far beyond his age; ... his special knowledge of literature ... enabled him to discourse elegantly, to understand fully, and to declaim most excellently from any work whether in verse or prose that came into his hands, unless it were from the more abstruse authors. He had such dignity in his whole person, and in his face such charm, that however much they might gaze, he never wearied the eyes of beholders
And that probably included Latin literature as well as English.