[5] On 7 April 1907, he married May Wynne, the daughter of Colonel Spencer Field of the Royal Warwickshire regiment; they had one son, also called William Sefton Brancker.

[6] During the First World War, Brancker held important posts in the Royal Flying Corps, including Director of Military Aeronautics.

[13] On 11 May 1922 he was made Director of Civil Aviation,[6] and worked assiduously to stimulate British interest in the subject among local authorities and flying clubs.

Together with Lord Thomson, the Air Minister, Brancker was killed when the airship R101 crashed near Beauvais, France, on 5 October 1930, during its maiden voyage to India.

In 1996, British Airways (BA) named one of its newly delivered Boeing 777s (G-ZZZB) "Sir William Sefton Branker" [sic] in recognition of his work.

Kenmore Park housing estate in Kenton, Harrow, has a number of its roads named after aviators including Brancker.