With varying degrees of commitment (usually minor), Richardson immersed herself in various philosophical movements of the period. She did much of her reading at the British Museum 's Reading Room, which she revered, but elsewhere she sat in both on casual discussions and on more formal meetings about contemporary politics and religion. She tried such political organizations as the Independent Labour Party , Conservative Primrose League , suffragists, Russian anarchist, and the Fabian Society , whose meetings she attended between about 1903 and 1906. Among religious denominations, she sampled Roman Catholic , Quaker , and Unitarian congregations. She considered them fascinating secret societies to each of which in turn I wished to belong and yet was held back, returning to solitude and to nowhere, where alone I could be everywhere at once, hearing all the voices in chorus.

In her MemoirsLMH writes of her family's experiences during the anti-Catholic Gordon Riots of June 1780. The family fled their house for fear of the rioters, and went to Clapton in north-east London, where they were sheltered by friends. Both LMH 's family and the family they stayed with were mistaken for Catholics. She writes of watching the fires, and of friends whose houses were destroyed.

She later entered municipal politics in the London borough of Marylebone, making an impassioned speech in support of the Socialist candidate. After that she was adopted as candidate for several elections herself, but was never successful in the poll. More than once, in Birmingham and again in Marylebone, she was harrassed on account of her Jewish name. She says she was always a committee Socialist: weak on dates or figures, good on the topic of housing, vulnerable as a Catholic on birth control. She had been adopted as a candidate for Sevenoaks when she realised that her health would not allow her to stand. She wrote in her first book of memoirs about the Labour Party, with a passage on its prominent women, but at the same date, 1933, she sounded quite respectful of the one-party (Fascist) condition of Italy, and the energy of Mussolini .

HL formulated her political creed in a letter in French to Arvède Barine in 1901: she was, she said, solidly (carrément) anti-Catholic, anti-militarist, anti-nationalist, very much a republican. The only people she could love were the weak, the humble, the unhappy or unfortunate; women, she added, generally belonged in these categories.

She wrote, in 1886 and 1891-2, several letters protesting against the first and second Home Rule Bills which sought to reduce British political and religious control over Ireland. Her anti-Home-Rule stance was no doubt shaped by Evangelical distrust and distaste for the Catholic Church .

When she wrote of her hatred of Enclosure Bills, and her pleasure when some glorious obstinate bumpkin of the true John Bull breed stood up against a Lord of the Manor to oppose them, she seemed to be thinking more of the beauty of the landscape than the fate of its inhabitants. She wrote on 2 March 1829 that she was delighted about the Catholic Emancipation Act (which was shortly to receive the royal assent); she looked to it to bring peace to Ireland. The following year she assumed on a visit to London that she would mingle socially with Whigs and largely avoid Tories; but she was dreading the spread of liberal opinions. She told a friend who opposed the Reform Bill that she supported it because she saw it as the only preservative against a much worse state of things. If we have not reform we shall have revolution. In 1833 she announced to an Irish friend: I am turned O'Connell ite, partly from love of his speeches.

WMCN had little hope she could secure a pardon for a Catholic rebel, but nevertheless she tried. She drummed up support, appeared regularly in the gallery at the House of Lords , organized a petition and went to court to present it herself to the king (whom she, like other Jacobites, called the Elector). When George I refused to take the paper; she clutched his robes and held on while he dragged her bodily across the room. This violence on the part of the monarch made a bad impression; Lady Nithsdale became a focus of sympathy and even something of a popular heroine. The petition was in the end read to the king, but it did not have the desired effect.

CGOB later underwent a period of divided allegiance which resulted in disillusionment with the Irish political movement. When the story of Parnell's adultery broke and the Catholic Church turned against him, she continued to support him. But during the last part of her life she shifted her activities in the direction of her interest in the developments of co-operation and mutual credit associations . . . and in the work of the Gaelic League.