The day after nineteen-year-old Betty Bulwer-Lytton, daughter of the Earl of Lytton, accepted a proposal of marriage from the rising Conservative politician Gerald Balfour, she received a different kind of proposal, a letter from a woman she barely knew, proposing ‘an intimate woman friendship’.

Lady Frances Balfour, daughter of the Duke of Argyll, was married to Gerald’s younger brother Eustace. But, she explained to Betty, for the past five years she had been in love with Gerald. He had a room in their house and they had been living in ‘the closest friendship’. ‘I do not think there has been a thought in my mind which has not been told him, or that I have passed one minute away from him that I could have spent in his company.’ Frances had acted as his political ‘wife’ as he campaigned for Parliament for the first time. Now he was to be married. Could Betty, rather than supplanting Frances, make a place for her?

Betty’s saintly acceptance of this extraordinary proposition led to the newly­weds moving into the same Kensington street as Frances and Eustace, the four living in and out of each other’s houses (although not their beds: it was not such a radical experiment in living) in what they referred to as