[2] Her brother Sackville FitzRoy Henry Lane-Fox died unmarried in 1879 (before their father's death) and her sister was Violet Herbert, Countess of Powis, later suo jure Baroness Darcy de Knayth.

At the same time the House of Lords found that her father had held the barony of Darcy de Knayth and confirmed it in favour of her sister, Violet Herbert, Countess of Powis.

[3] Due to the peerages which thus came to her, Marcia Pelham brought 153 armorial quarterings to her husband's family.

In 1920, the countess was appointed an Officer of the Order of the British Empire in recognition of her role as Commandant of Brocklesby Hall, her husband's ancestral home, which had served as an auxiliary hospital during the First World War.

After the 3rd Earl's death in 1875, his widow married John Maunsell Richardson, a Cambridge cricketer and Member of Parliament for Brigg.