At the 1929 UK general election (30 May), Rathbone was elected Independent MP for the Combined English Universities, becoming the first Somerville College alumna in the Commons.
On 30 May 1929, polling day of the United Kingdom general election, Eleanor Rathbone was elected as the Independent Member of Parliament for the Combined English Universities. This victory made her one of the relatively small cohort of women in the House of Commons at the time and the first alumna of Somerville College, Oxford, to be elected to Parliament.
Rathbone's election came just months after women in Britain achieved full electoral equality with men under the Representation of the People (Equal Franchise) Act 1928, which lowered the voting age for women to 21. Her success as an independent, unaffiliated with any major party, was a testament to her established reputation as a formidable social reformer and expert on family welfare, built over two decades of activism in Liverpool.
As MP for the Combined English Universities, Rathbone represented graduates of several English universities rather than a conventional territorial constituency, a peculiarity of the British electoral system at the time that allowed her to focus on national policy issues, particularly family allowances, women's rights, and later, the plight of refugees from fascism. She held this seat continuously until her death in 1946, using her platform to press for the causes she had championed since her earliest days in Liverpool politics. Her election remains a landmark moment in the history of women's representation in the British Parliament.