a member of the council for Mary's estates, based in Paris. Responses to the Raid of Ruthven Some of Castelnau's letters to Scotland were intercepted and examined and copied by English diplomats including Robert Beale. In September 1582, Elizabeth I was told that Castelnau secretly conveyed letters to Mary, and to her supporters in Scotland. Walsingham asked the ambassador in France, Henry Cobham, to advise Henry III of France and the Queen Mother, Catherine de' Medici, of the situation, and that their representative in England could be more circumspect in the handling of Mary's letters. Elizabeth had no wish to foment further disquiet in Scotland following the recent pro-English Raid of Ruthven. Cobham was told that Castelnau's actions were doubtless correct and in accord with the traditional Auld Alliance or amity. Mary sent several letters to Castelnau, some in cipher, hoping for a strong French response against the Ruthven Regime. In April 1583, Willam Cecil made a list of Castelnau's previous letters and communications with a Scottish intriguer Archibald Douglas and the favourite of James VI, Esmé Stewart, 1st Duke of Lennox. A spy using the name "Henry Fagot" offered to bribe Castelnau's secretary to keep Francis Walsingham informed of ciphered letters and the key to the lettre quartallé or cartelée code used in his correspondence with Mary, Queen of Scots. Code work in Mary's household Mary asked Castelnau to take special care of her secret correspondence and pay the couriers well. He should pretend the money was for gold and silver embroidery thread. She sent cipher keys or alphabets to his secretary Claude de Courcelles. In 2023 around 57 coded letters to Castelnau from Mary, Queen of Scots, were discovered in the Bibliothèque nationale de France and deciphered. The letters were probably put into cipher by Mary's secretaries Gilbert Curle, Claude Nau, and Jérôme Pasquier, who was variously recorded as master of her wardrobe, a groom of her chamber, a clerk and a household treasurer. Alexandre Labanoff, a 19th-century editor of Mary's letters, was unable to find a key for this cipher. Curle, Nau, and Pasquier were taken to the Tower of London in September 1586 during the discovery of the Babington Plot.John Hungerford Pollen, Queen Mary and the Babington Plot (Edinburgh: Scottish History Society, pp. clxxxv-clxxxvii Amias Paulet had noticed that Pasquier was "half a secretary". Pasquier was asked by Thomas Phelippes about recent intrigues, the older Throckmorton