Following the defeat of Germany in World War One, Namier (age 31) joined the British delegation at the Versailles Peace Conference of 1919. Based on his personal background, Namier maintained a firm personal interest in Russian affairs; however, he was also seen as one of the biggest enemies of the newly-independent Polish state in the British political environment. During the Polish–Soviet War his relationship with the Polish delegation was highly antagonistic and his attitude towards Poland and Polish territories openly hostile. Namier was later accused of changing the British proposal – the "Curzon Line" – for the eastern border of Poland by leaving the city of Lviv (in Polish, Lwów) and the Oil Basin on the eastern side when the British Foreign Office sent a cable to the Commissar for Foreign Affairs of Bolshevik Russia, . The Polish delegation had no knowledge of the existence of Line "A" whatsoever since the idea of handing Lwów over to the Bolsheviks was rejected by Prime Minister Władysław Grabski at the very beginning of talks. Lwów had never been under the Moscow rule in its history. Prof. Piotr Eberhardt from the Polish Academy of Sciences speculates that Lloyd George could have been aware of Namier's modification; Bartłomiej Rusin refutes the claims that Namier was responsible and calls him "merely a convenient supplier of anti‑Polish arguments". The earlier-approved compromised version of Curzon Line which was approved at the Spa Conference in Belgium was renamed by Namier as Curzon Line "B". Chicherin relayed this document to Lenin who rejected it nevertheless, assured of his victory over Poland followed by a planned annexation of its entire territory.