He married Eleanor Louisa Henry, the illegitimate daughter of the English astronomer
Richard Sheepshanks (1794–1855). He had five sons and one daughter. • Oswald Valentine, author, salesman and international traveller for
Encyclopædia Britannica. • Robert, a recluse who died from injuries when he was hit by a lorry. • Leonard, who died after a long battle with substance abuse. •
Walter Sickert (1860–1942), an influential post-impressionist painter and printmaker. • Bernhard, a painter and architectural engraver, suffered from depression and alcoholism. • Helena (1864–1939), later
Helena Swanwick, a suffragist and pacifist. None of his children produced grandchildren. He is buried in
Brompton Cemetery, London. ==Artworks and personal papers==