Does language matter? Hugh Trevor-Roper thought that it did. Nowadays it is fashionable to rate self-expression above precision. But Trevor-Roper believed that without clarity of language there can be no clarity of thought. Like Orwell (whom he admired), he knew that freedom is endangered when language becomes corrupt. These journals were written during the Second World War, when the defence of the English language against all forms of attack seemed especially important. They remained unseen until after his death in 2003, when they were discovered hidden in his house. Their publication now reveals a new side to the formidable historian. The notebook entries exhibit an intellectual in the process of formation: an isolated, reflective individual training his mind and refining his style.

Though only twenty-five when war broke out in 1939, Trevor-Roper had already finished his first book, a biography of Archbishop Laud. Influenced by his friend A J Ayer, he had formed the view that lucidity was the sole criterion of good writing. Trevor-Roper had swallowed Ayer’s prescriptions as a purgative