Sandhurst was the youngest of the seven children of Robert Fellowes (1779–1869) of Shotesham Park, Norfolk, and his second wife, Jane Louisa Sheldon (d.

After her husband's death in 1876 Lady Sandhurst became increasingly involved in both spiritualism and Liberal politics.

An active philanthropist, Sandhurst ran her own home for sick children in the Marylebone Road.

In January 1889, Lady Sandhurst was elected to the London County Council at the head of the poll.

[3] In recognition of her sympathy towards Ireland, in September 1889, Sandhurst was awarded the Freedom of the City of Dublin.