I want to know the answer to the following question:
In what century did Old English first develop?
All the background I'm provided with is that "Celtic speech also remained established in certain parts of England: Medieval Cornish was spoken all over Cornwall and in adjacent parts of Devon, while Cumbric survived perhaps to the 12th century in parts of Cumbria, and Welsh may have been spoken on the English side of the Anglo-Welsh border.". Is that enough to answer the question?
Answer: no