Their father, Nathan Rothschild, 1st Baron Rothschild, head of the English branch of the family, had a guarded attitude towards Zionism, but he died in March 1915 and his title was inherited by Walter.  Prior to the declaration, about 8,000 of Britain's 300,000 Jews belonged to a Zionist organisation.
Ayah mereka, Nathan Rothschild, 1st Baron Rothschild, kepala cabang Inggris dari keluarga tersebut, memiliki sikap terpandu terhadap Zionisme, namun ia meninggal pada Maret 1915 dan gelarnya diwariskan oleh Walter.  Sebelum deklarasi tersebut, sekitar 8,000 dari 3000,000 Yahudi di Britania masuk ke sebuah organisasi Zionis.