Lantern slide of Gate of British Legation, Peking (Beijing). In diplomacy, a legation was a diplomatic representative office lower than an embassy. Where an embassy was headed by an Ambassador, a legation was headed by an Envoy Extraordinary and Minister Plenipotentiary. The distinction between a legation and embassy was gradually dropped following World War II. All diplomatic representative offices are now designated as embassies or high commissions.. Part of Box 159 Pekin, slide no. 43