The 43 Group was an English anti-fascist group set up by Jewish ex-servicemen after the Second World War. They did this when, upon returning to London, they encountered British fascist organisations such as Jeffrey Hamm's British League of Ex-Servicemen and later Oswald Mosley's new fascist party, the Union Movement. The activities of these fascist groups included antisemitic speeches in public places, and from the rank-and-file fascists, violent attacks on London Jews and Jewish property.[1] Group members broke up far-right meetings, infiltrated fascist groups, and attacked the fascists in street fighting.[2]
Their newspaper, On Guard, was published from 1947 to 1949
https://en.wikipedia.org/wiki/43_Group