Davies was born at Gerlan, Bethesda, Caernarfonshire, the son of David Davies a quarry official. He was educated in Bethesda and at Liverpool College. He worked as a clerk in insurance offices in Wrexham and Sheffield until he qualified as a solicitor in 1899. He passed his final Law Society examination with first-class honours, winning the Law Society prize in 1899, after which he established a law practice in Caernarfon where he lived for the rest of his life. He was also director of several companies and solicitor for the North Wales Quarrymen's Union. He died at Caernarfon in 1939. He founded the Caernarfon solicitor firm - 'Ellis-Davies and Co' that is still in existence today and has his great grandson as one of the partners.
During the First World War, Davies was one of a number of Welsh MPs who broke with Prime Minister David Lloyd George over his conduct of the war. Davies regarded Lloyd George's ministry as bellicose and illiberal, conflicting with his own strongly held pacifist and pro-labour views. Although Ellis Davies was never really close to Lloyd George he knew him quite well being a Caernarfonshire MP and his journal records a number of occasions when they discussed political questions or worked together on specific projects. At the 1918 general election Davies, as a supporter of the Asquithian Liberals, did not receive the coalition coupon and was heavily defeated, coming bottom of the poll.
Labour and Liberal Nationals
Davies joined the Labour Party in 1936, only to leave early in 1939 because of its foreign policy. He believed that Neville Chamberlain’s policy of appeasement was more likely to keep the peace than Labour's support for intervention abroad. As a supporter of social reform, he felt that there was plenty of work to be done to improve social conditions at home and this could not be done if the country was at war. He then chose to associate himself with the Liberal Nationals, the allies of Chamberlain's Conservative government, although at the age of 68 years it was probably not in the hope of finding another seat.
Papers
The papers of Ellis Davies, 1889–1939, comprising his diaries, journals, correspondence, press cuttings, addresses, articles and memoirs, together with printed and typescript memoranda, reports, policy documents and official publications are deposited at the National Library of Wales.