Sophia de Mello Breyner and Francisco Sousa Tavares created a code that the PIDE secret police never discovered in the correspondence they exchanged while the lawyer was detained for opposing the Estado Novo regime, their son Miguel Sousa Tavares told Lusa. Beyond accompanying his mother on visits to Caxias prison, Miguel Sousa Tavares was tasked with helping her draft letters and 'translate' the messages sent by his father. The son recalled that they had invented a brilliant code to share political secrets within the resistance circle against the Estado Novo. Miguel Sousa Tavares swore to his mother that he would never reveal the enigma contained in the letters, which required a creative writing style to ensure the PIDE did not suspect a key was hidden within. The code was used whenever Francisco Sousa Tavares was imprisoned and able to communicate with his wife. Miguel Sousa Tavares, who was the only child entrusted with the secret, noted that the code was used during his father's detention related to the 'Ballet Rose' scandal in 1967, which also involved Urbano Tavares Rodrigues and Mário Soares.