Volume 1, page 55, sitting number 425.
Ernst, 4th Prince of Leiningen (1830-1904), was Queen Victoria’s half-nephew. His father was Charles, 3rd Prince of Leiningen, Queen Victoria’s half-brother through the first marriage of her mother, Victoire of Saxe-Coburg-Saalfeld (1786-1861), to Emich, 2nd Prince of Leiningen (1763-1814). The Prince was an Admiral in the British Navy and a Captain of the Royal Yacht Albert. He served in Burma and the Baltic and was Commander-in-Chief of the Nore. Prince Ernst married Mary of Baden, daughter of Grand Duke Leopold of Baden. On 7 July 1865, he stood as one of the godparents of the future King George V.
The image appears in volume one (1860) of the Silvy daybooks in the National Portrait Gallery archives. Of the twelve extant volumes, this is the only one that does not give specific dates for the sittings.