With the arrival of the Romans in the first century AD, Latin became the language of administration, trade, and education in Britain. The influence of Latin on the British Isles was significant and lasted for centuries, with Latin words continuing to be used in English even today.
The influence of Celtic languages, however, did not disappear with the arrival of the Romans. In fact, many words in English have Celtic roots, such as "crag," "bog," and "loch," to name a few. These words have been a part of English's evolution since the beginning and continue to shape the language today.