Royal Standard of Alexandra of Denmark , Queen Consort of Edward VII of the United Kingdom and the British Dominions (1901-1910) and British Queen Dowager (1910-1925)
Queen Alexandra's arms were the Royal Coat of Arms of the United Kingdom impaled with the arms of her father, Christian IX of Denmark:
Quartered by the Cross of Dannebrog 1 Denmark, 2 Schleswig, 3 per fess, in chief Sweden, in base, Iceland, Faroe Islands and Greenland, 4 per fess in chief Wends, in base Goths.
Middle shield: Quartered: 1 Holstein, 2 Stormarn, 3 Dithmarschen, 4 Lauenburg. Top shield: Per pale, Dexter Oldenburg, Sinister: Delmenhorst.

Sources: [1], 70px and 70px