A selection of British and German contributions will be presented, namely the first radar of Hülsmeyer in Germany and the Chain Home (CH) as the first air defense system. Next Klein Heidelberg a Ger- man bistatic air defense system is explained, which at that time was decades ahead of its time. The lecturer describes the use of Chain Home to detect V-2 rockets and hence the first ballistic missile defense system radar BIG BEN. In addition the impact of the famous Bruneval raid and the following technological analysis of the German equipment including the interrogation of the captured radar operator is presented.