In 1900 he succeeded to the vast fortune of his great-uncle, Lord Armstrong. The following year he gave £100,000 (equivalent to £13,712,955 in 2023),[4] for the building of the new Royal Victoria Infirmary in Newcastle upon Tyne, for which the city conferred upon him the honorary Freedom in July 1901.[5] The original 1753 infirmary buildings at Forth Banks near the river Tyne were inadequate and impossible to expand.[6]
In 1903 he was raised to the peerage as Baron Armstrong, of Bamburgh and Cragside in the County of Northumberland,[8] a revival of the barony which had become extinct on his great-uncle's death three years earlier.
Lord Armstrong was married three times. He married firstly Winifreda Jane Adye, daughter of General Sir John Miller Adye, in 1889. They had one son and one daughter. After her death in December 1914 he married secondly Beatrice Elizabeth Cowx,[9] daughter of Jonathan Cowx, in 1916. After her death in November 1934 he married thirdly Kathleen England (b. 12 August 1898), daughter of Reverend Charles Thorpe England, in 1935. The last two marriages were childless. Lord Armstrong died in October 1941, aged 78, and was succeeded in the barony by his only son, William. Lady Armstrong died on 2 September 1970.
^"Court and social". The Times. No. 36510. London. 18 July 1901. p. 9.
^McKenzie, Peter (1983). W.G. Armstrong: The Life and Times of Sir William George Armstrong, Baron Armstrong of Cragside. Longhirst Press. ISBN0-946978-00-X.
^"University intelligence". The Times. No. 36573. London. 30 September 1901. p. 4.