In April 1917, Hyamson was made the editor of "The Zionist Review" (the newspaper published by the Zionist Federation). In October of that year Ze'ev Jabotinsky proposed a Jewish Bureau for the UK government's Department of Information, however as Jabotinsky was preoccupied with organising the Jewish Legion, the role fell to Hyamson. His work at the Bureau in December 1917 involved distributing news items that illustrated the British government's support for Zionism and the growing support for Zionism among the world's Jews. The main focus of his output was in America, where he distributed cables to two Jewish daily newspapers, "The American Hebrew" and "American Jewish Chronicle". At the same time, Hyamson became a senior member of a new committee created by the London Zionist Federation designed to publicise the Zionist message. The Jewish Bureau in the Department of Information and the London Zionist Federation ran in close contact, with members of the Federation writing much of the material for the Bureau. This enabled the Department of Information to hide the official nature of its propaganda, and allowed Zionists to produce material to promote their movement. Examples of Hyamson's work for the Department of Information included "Great Britain and the Jews", a pamphlet he wrote in response to the Balfour Declaration of 1917 that explained how the agreement was a part of a long tradition of British sympathy for the Jews. A film "The British Re-conquering Palestine for the Jews", made after General Allenby had taken Jerusalem, which was sent to Jewish centres around the world. His book "Palestine: The Rebirth of an Ancient People" set out "the benefits the recent Jewish colonisation of Palestine has brought to the land". Hyamson also made Jabotinsky the official British journalist for Zionist affairs in Palestine.