the Britons
Reading Our Magnificent Bastard Tongue by John McWhorter (9781592404940). The author claims that spoken Old English existed just long enough for the Anglo-Saxon-Jutes to conquer the the Britons, then the conquered Britons immediately mangled the language, producing something very akin to Middle English within a generation. But the A-S-J scribes continued to write a dead language for five hundred years. This is why English is so unlike other Germanic Tongues.