Reginald Tower served in the following diplomatic positions:
- 1885–1892: Diplomatic Attaché in Constantinople
- 1892–1893: Second Secretary to the British Legation in Madrid
- 1893–1894: Second Secretary to the British Legation in Copenhagen
- 1894–1896: Second Secretary to the British Legation in Berlin
- 1896–1900: Second Secretary to the British Legation in Washington, D.C.
- 1900–1901: Secretary of the British Legation in Peking
- 1901–1903: Envoy Extraordinary and Minister Plenipotentiary to the King of Siam, and Consul-General in Siam, his first position as head of a diplomatic mission. He arrived in Bangkok to take up his post in late December 1901.
- 1903–1906: Minister Resident in Bavaria and Württemberg
- 1906–1910: Envoy Extraordinary and Minister Plenipotentiary in Mexico
- 1910–1919: Envoy Extraordinary and Minister Plenipotentiary in Argentina
- 1911–1919: Minister Plenipotentiary in Paraguay
- 1919–1920: Temporary Administrator to the Free City of Danzig, and High Commissioner of the League of Nations at Danzig
In 1907, while British Ambassador to Mexico, Tower donated a trophy in order to establish the Copa México. For this reason, in the early days of the competition it was known as the Copa Tower.
Tower was the British Ambassador in Argentina and Paraguay for the duration of the First World War. During the war years he worked energetically to secure British wheat imports from Argentina, and to persuade British-owned companies to suspend German employees and refuse to do business with German firms.
In 1904 Tower was awarded the Grand Cross of the Frederick Order of Württemberg. He was made a member of the Royal Victoria Order in 1906, and a Knight of the Order of St Michael and St George in 1911. Tower's career ended with his retirement in 1920. Three portraits are held by the National Portrait Gallery, London.
- Who's Who UK online
- "Tower, Reginald Thomas (TWR879RT)". A Cambridge Alumni Database. University of Cambridge.
- "No. 27372". The London Gazette. 5 November 1901. p. 7144.
- "Court circular". The Times (36651). London. 30 December 1901. p. 7.
- Gravil, Roger. 'The Anglo-Argentine Connection and the War of 1914–1918' in Journal of Latin American Studies, 1977, pp. 59–89
- National Portrait Gallery website