This article examines the policy and strategies of the Shipping Federation, which was the most aggressive employer association in the United Kingdom during the pre-war period. Using a vast array of sources, including several series of minutes and the financial records and ledgers of the association of shipowners, this article provides a number of insights into the Federation’s organizational and operational structure, the subcontracting of labour replacement to professional or commercial strike-breaker agencies as well as the delegation of protection tasks to vigilante groups. It looks at the transnationalization of its anti-labour schemes and the formation of an international body of strike-breakers, the International Shipping Federation, to deal with the question of maritime labour at home and abroad. The article emphasizes the shipowners’ propositions to form their own private security organization in response to the Liberal government’s assertion of neutrality in labour disputes. It shows their determination to use violence, including the presence of firearms, to suppress efforts by unions to achieve recognition and the monopoly over the supply of labour and hiring procedures. The purpose of the article is to demonstrate the inclination of certain sectors of British industry to employ violent, illegal and inherently subversive means to protect their managerial authority from both the opposition of trade unions and the increasing encroachment of the state into industrial matters.