After he entered his family's coal business in 1879, Thomas promoted several mergers of mining companies and in 1913 formed Consolidated Cambrian, Ltd., a huge mining organization. For 22 years he was a Liberal member of the House of Commons. After surviving his passage on the British steamship Lusitania (torpedoed by a German submarine, May 7, 1915), he went to the United States to direct the supplying of U.S. munitions to Great Britain. Prime Minister David Lloyd George appointed him president of the Local Government Board (December 1916) and controller at the Ministry of Food (June 1917), in which office he stabilized prices, regulated supplies, and gradually (from February 25, 1918) instituted a rationing system, which became fully effective in the month of his death. He was created a baron in 1916 and a viscount in 1918. (The viscountcy went to his only child, a daughter, after his death.)