Autograph Letter Signed with initial, to “My dear Mildred & Blanche”, offering “my Box at the Opera”, with instructions about carriages. 1 page 7 x 4 inches, in good condition, with the address leaf also initialled by Wellington (”Lady Mildred Cecil, Arlington Street / Immediate”), with Wellington’s armorial seal in red wax. London, 17 April 1841. A letter entirely in the hand of the first Duke of Wellington (1769-1852). Lady Mildred Cecil was the eldest daughter of the second Marquess of Salisbury and sister of the prime minister. On 7 July 1842 she married the politician Beresford Hope, the stepson and heir of General Viscount Beresford, Marshal of the Portuguese Army, and one of Wellington’s commanders in the Peninsular War.