A file of signals intelligence reports, messages, and correspondence issued by the Government Code and Cypher School and sent by the head ('C') of the Secret Intelligence Service (MI6) to the Prime Minister, Winston Churchill. This file includes the following reports referring to the Prime Minister's (PM's) Moscow visit, in response to the PM's note of October 23: from the Japanese ambassador in Moscow, that Churchill is in Moscow, and noting friction over the Polish question, on October 16; from the Japanese ambassador in Ankara, detailing talks in Moscow on Poland and the Balkans, on October 18 and 19; and another report on the Moscow talks, stated to be Turkish information, on October 17; from the Portuguese ambassador in London, passing on Brazilian information that Stalin told Churchill that Poland is a Soviet question, on October 20; from the Spanish ambassador in London, detailing Moscow talks on Poland, and the war situation, on October 13; from the Spanish minister in Istanbul, that Churchill and Eden are to visit Turkey after Moscow, on October 12; and from the Turkish ambassador in Moscow, that Churchill and Eden's visit was probably on the Polish question, on October 10.