During this time he created an extensive network of fictitious sub-agents living in different parts of Britain. Because he had never actually visited the UK, he made several mistakes, such as claiming that his alleged contact in Glasgow "would do anything for a litre of wine", unaware of Scottish drinking habits or that the UK did not use the metric system. His reports were intercepted by the British Ultra communications interceptions programme, and seemed so credible that the British counter-intelligence service MI5 launched a full-scale spy hunt.