On 3 September 1883 she married Lt.-Col. Sir Theodore Francis Brinckman, 3rd Bt. (1862 - 1937), but they divorced in 1895, after a long separation. Her second marriage was to a bankrupt George Frederick William Byron, 9th Baron Byron of Rochdale, in 1901. He died in 1917. During this time she was an active suffragette. In 1917 Lucy, then Baroness Byron, was appointed Dame Commander, Order of the British Empire (D.B.E.) for her support of a home for nurses who had served in the First World War.
When Sir Robert showed her his will, Lucy tore it up telling him that one million pounds was not good enough. Sir Robert then suffered a series of mental disorders and Lucy employed a food-taster to ensure that he was not being poisoned. Even so Sir Robert mysteriously died on his yacht Liberty on 14 April 1926, leaving his widow roughly £5.5 million.
She was described as paranoid with religious delusions and declared mentally unfit to manage her own affairs, but she left Jersey in the Liberty. She then negotiated with the British Government the payment of £1.6 million in death duties. Her political opinions were extreme (she supported Mussolini). According to the Oxford Dictionary of National Biography "she paid for nine by-election meetings by the British National Government to be disrupted".
The Royal Air Force's entry for the 1931 race for the trophy was hindered by political opposition. On January 15, 1931, the Air Ministry refused a last minute request by the Royal Aero Club for funds for an entry. The Ministry also forbade the use of the aircraft that competed in the 1929 race; forbade RAF pilots of the High Speed Flight who were trained to fly these seaplanes, to take part; and said that it would not police the race course in 1931 in the busy shipping lanes in the Solent.
Many newspapers backing the opposition Conservative Party wanted to put pressure on Ramsay MacDonald's Labour government. One newspaper sent a telegram to MacDonald stating that: "To prevent the socialist government from being spoilsports, Lady Houston will be responsible for all extra expenses beyond what Sir Philip Sassoon (President of the Royal Aero Club) says can be found, so that Great Britain can take part in the race for the Schneider trophy."
The gift gave Lucy Houston an opportunity to attack the Labour government, with the declaration: "Every true Briton would rather sell his last shirt than admit that England could not afford to defend herself." The Prime Minister could not ignore the patriotic fervour that she generated and so yielded.
There were only nine months to prepare and so Supermarine's designer Reginald Mitchell could only update the existing airframes. Rolls-Royce increased the power of the R-Type engine by 400 hp to 2,300 hp. The improved aircraft Supermarine S.6B won the trophy, though the technical achievement is slightly tarnished by the fact two S6Bs and an S6 were the only participants. (One S6B later broke the air speed record.)
Lady Houston's gift provided a valuable impetus to the development of engine technology that would ultimately vital in the Second World War in particular the Battle of Britain. The lessons learned in building racing seaplanes also helped Reginald Mitchell to develop the Supermarine Spitfire. As Arthur Sidgreaves, the managing director of Rolls Royce, commented at the time: “It is not too much to say that research for the Schneider Trophy contest over the past two years is what our aero-engine department would otherwise have taken six to 10 years to learn.”
She put a large illuminated sign on her yacht saying: "DOWN WITH MACDONALD THE TRAITOR!". In a telegram to the Prime Minister she said:
In 1933 she financed the Houston-Mount Everest Flight Expedition, in which aircraft flew over the summit of Everest for the first time. This was to show opposition to granting independence to India.
In October 1934 Lady Houston sent a cable to the winners of the MacRobertson England to Melbourne Air Race, Tom Campbell Black and C.W.A. Scott. The following is a transcript from The Daily Mirror newspaper, Wednesday, October 24, 1934, page 3. "Brave Men Of My Heart- Lady Houston, in a cable to Mr. C.W.A. Scott at Melbourne, said:- "Your achievement has thrilled me through, oh brave men of my heart." "If this does not make the Government sit up, nothing will." "Sleep well and feel proud of yourselves, as we all are." "Rule Britannia. God bless you both."
Her letters were usually written on coloured paper with violet ink. She was so upset by the Abdication Crisis in 1936 that she stopped eating and died of a heart attack on December 29 1936, at the age of 79.
She had no children and no legal will was found, so the money (£1.5million) was informally passed to a friend.