Sharing a common economic culture without knowing anything about it. The French and British socialist experts in the 1970s Conventional wisdom tends to oppose the 1970 British Labour Party and the French Socialist Party in what concerns their views on the economy. The former, intermittently in office since 1945, accepted to lead austerity policies, perceived as the only means to defeat spiralling inflation and balance of payments imbalances. On the other hand, the latter and its communist allies supported a radical economic alternative based on a substantial enlargement of public sector and a constraining planning system. A more careful reading of the programmes designed by both parties in the early 1970s allows us to significantly revise this assessment. The sections of these documents that address economic issues actually offered astonishing resemblances, all of them being based on nationalisation, a reinforcement of planning mechanisms and a plea for industrial democracy. This article aims at reflecting upon the main causes of this economic convergency. By combining a transnational approach with a careful attention to the national framework in wich both parties developed their policies, the article shows that the common economic culture emerging in the programmes can only be understood by examining the case of the economic experts involved in the drafting of these documents. While rejecting explanations in terms of Sonderweg, this work suggests to consider the relationship between the British and French socialists as an interesting case study of transnationalization of economic culture in the Western European social-democracy and of its limits.