Life after the First World War
Following her brother's death, Parsons did not resume her role as a director of the Heaton Works, possibly because of a rift with her father. As evidence of her continued aspirations in engineering she became a member of The Royal Institution of Great Britain in 1918, continuing to be a member until she died.
She and her mother, Katharine, Lady Parsons, were among the founders of the Women's Engineering Society alongside Eleanor, Lady Shelley-Rolls; Margaret, Lady Moir; Laura Annie Willson; Margaret Rowbotham and Janetta Mary Ornsby. The organisation promoted the retention of women engineers after the First World War by opposing the Restoration of Pre-War Practices Act 1919, as well as supporting engineering as a career for women. Rachel Parsons became the first president of the Women's Engineering Society on 23 June 1919, and served until 1921.
On 9 April 1919, with Blanche Thornycroft and Eily Keary, she was one of the first three women admitted to the Royal Institution of Naval Architects and from 1921 she became a lifelong member of the Royal Institute of International Affairs. She also held a Master Mariner's Certificate.
In 1920 Parsons was one of a group of eight women who founded the engineering company Atalanta Ltd, with her mother Katharine Parsons as chairman and one of the principal shareholders. All the employees were women and the director was Annette Ashberry. The company produced surface plates and machine models. It was initially based in Loughborough, where it was intended that the employees could receive further education at the Loughborough College of Technology. Atalanta moved to London, with premises initially in Fulham Road in 1922 and then Brixton Road in 1925. It was voluntarily wound up in 1928.
In 1922 Parsons bought 5 Portman Square, a large house in London, and began to host social events attended by the elite of London society. That year she became one of the few women members of the London County Council, representing Finsbury for the Municipal Reform Party, and sat on the Electricity and Highways Committee. She stood for Parliament in the 1923 election as the Conservative candidate in the constituency of Ince, Lancashire, but was not elected. She moved to the larger property of 5 Grosvenor Square in 1926 and continued as a society hostess. She put herself forward for selection as the Conservative candidate for Newcastle in 1940, but was not successful.
In 1940 she moved into the countryside at Sunningdale, Berkshire, purchasing Little Court, a Georgian-style house with twenty-five acres of land. However, she also maintained a London residence, living successively in two houses in Belgrave Square. Her interest in horse racing led her to buy the 2600-acre Branches Park estate at Cowlinge near Newmarket, Suffolk, in the 1940s where she built up a large stud farm, as well as in 1954 purchasing the Lansdowne House racing stable in Falmouth Avenue, Newmarket. She had several notable successes from her stables. These included wins in 1953 with Cavalleria, Golden God and Fraise Melba (trained by Geoffrey Brooke) followed by success with Le Dieu D'Or, Golden God and Fraise Melba under trainer Sam Armstrong.
