Born in St. Petersburg to British parents in 1891, Birse had native fluency in Russian which came from his schooling in the country. This was contrary to the practice of other British families there who sent their children back to the UK for their education. He joined the British Military Mission in Russia in 1917 as an interpreter. However, following the Bolshevik Revolution he moved to the UK and worked for a bank. This saw him sent to Poland and Italy where he learned those languages too. He returned to the military with the outbreak of war and was sent to Russia following the German invasion.