Latin was the language of the Roman Empire, and later of the Byzantine Empire, that was spoken throughout the empire; that is in all the provinces, that included modern-day france, Spain, Portugal, Italy and Britannia, as well as
islands and areas around these. From Latin were shaped the
languages of French, Portugese, Spanish, Reto-romanian, Italian, and the ENglish language owes over 70% (unless I am mistaken) to the influence of the Romans in the country. But Old English, I think, was largely the language of the Anglo-Saxons and early settlers of England; Latin did not touch it at all, as I understand. Middle English was a bit more like modern English..
I'm studying Spanish and Latin at the moment, and I can tell you the similarities between the two, and with words in the English language, are incredible.