Zaidman was a leading London Communist during the period of the 1930s to the 1950s. He was born in Jubilee Street in the East End to a Jewish family in 1903, but returned with his family to Rumania in 1911 or 1912. In Rumania he became a revolutionary and spent 3 years in prison where he was tortured, losing an eye and an ear.
In 1925 he was deported back to England. He settled in Hackney with his wife, Ray, and set up a valet shop. Many of his speeches were written on the back of handbills for this shop. Zaidman was a presser by trade but was victimised by his own union, and was thus forced to run his own business.
In the 1930s, the Zaidmans’ house in Hackney was used regularly for Communist Party discussions and political meetings. A Jewish study group was based at the house consisting of Zaidman, Alf Holland, Chimen Abramsky, Izzie Pushkin, and Julie Jacobs. All were Communists active in the Jewish Peoples Council Against Fascism and Anti-Semitism – a group that coordinated anti-fascism in the East End during the 1930s.
After the war Zaidman was prominent in the Workers’ Circle movement and also in the National Jewish Committee of the Communist Party. Although never a "national" figure in the Communist Party, he was well-known and was close to more prominent individuals such as R Palme-Dutt, Hyman Levy, George Rude, and Ivor Montagu. He died in 1963, and his funeral was attended by the leading Communist figures in Britain, an indication of the respect in which he was held.