British diplomatic intervination in ethiopia on behalf of the aggressor nation was evident in
the Italo-Ethiopian War of 1935-36. The British government, led by Prime Minister Stanley Baldwin, pursued a policy of appeasement towards Italy and initially remained neutral. However, as the conflict escalated, there were indications of British support for Italy's territorial ambitions in Ethiopia. For example, the British government allowed Italian planes to use their airspace to bomb Ethiopian targets, and they did not enforce an arms embargo against Italy.
Furthermore, the British facilitated talks between Italy and Ethiopia that resulted in the signing of the Hoare-Laval Pact in December 1935, which proposed a compromise that would have given Italy control of key Ethiopian territories. The pact was widely condemned, and public outcry in Britain forced Baldwin to distance himself from the agreement.
Overall, British diplomatic intervention in Ethiopia during the Italo-Ethiopian War was characterized by a lack of decisive action and an unwillingness to confront Italian aggression. This approach reflected a broader policy of appeasement towards fascist regimes in Europe, which ultimately failed to prevent the outbreak of World War II.