Not only were political parties and trade unions monitored, the press was also forced to toe the official line. The Algemeen Nederlands Persbureau (the largest news agency in the Netherlands) came under German censorship and reports about certain subjects were prohibited, obligatory, or undesired. The press was quickly cautioned not to write anything about the royal family. This censorship also applied to the radio. On 28 July 1940, Queen Wilhelmina spoke for the first time to the Dutch people from London via BBC (Radio Oranje). The Germans recognised the danger in this and immediately prohibited anyone from listening to the BBC. Initially Jews were prohibited from having a radio at home (April 1941), but later this applied to all Dutch people. One of the fears harboured by the Germans was that, in case of an invasion from England, the British would be able to instruct the Dutch population by radio. Theatres, literature, and other forms of art were curtailed. The Germans set up a Kultuurkamer; artists who were not members were no longer allowed to publish, perform, or exhibit. Libraries were no longer allowed to lend out anti-German literature.