Appointed Director with the help of a reference from Frederic William Burton, Director of the National Gallery, London, Walter Armstrong (1815-1918) was an established art critic, with many scholarly publications to his name. He was regarded as an expert in seventeenth century Dutch painting and eighteenth century British art, and was responsible for improving the Gallery's catalogue by providing a much more detailed and comprehensive account of the collection. He purchased a number of important works including La Main Chaude by Rembrandt and Uccello’s Virgin and Child, as well as works by several Dutch artists including Pieter de Hooch and Salomon van Ruysdael. He also developed the Irish collection and, following the death of Walter Osborne, bought three works by the artist.
Important bequests during Armstrong’s directorship include: Henry Vaughan’s (1809-1899) bequest of a collection of thirty-one watercolours by Joseph Mallord William Turner (1775-1851) in 1900; Frederic William Burton’s (1816 – 1900) watercolour painting Hellelil and Hildebrand, The Meeting on the Turret Stairs by Margaret Stokes in 1898; and in 1897, one of the most important collections representing the Grand Tour was offered by Countess Milltown of Russborough House, County Wicklow, in memory of her late husband the 6th Earl of Milltown. The Milltown’s gift to the Gallery was immense. Valued at the time at £40,000, it consisted of approximately 223 pictures, 48 pieces of sculpture, 33 engravings, 528 pieces of silver, 200 pieces of furniture, a library and various miscellaneous objects. The significance of the gift can best be understood in the context of the annual grant-in-aid to the Gallery which, in 1905, stood at £3,096.
As a direct result of the Milltown Gift, a perennial request to provide for an extension to the Gallery was acted upon. In a letter to the Treasury, Armstrong emphasised ‘that Lady Milltown’s offer supplies a further and imperative necessity for that extension of the Gallery building which they have felt is their duty for some years past to urge on the Government.’ The Treasury finally reacted positively and plans for a new extension, which had first been designed in 1892 by the architect Sir Thomas Newenhan Deane, were revisited and resubmitted. Work on the new wing began in 1900 and following the death of Thomas Newenham Deane in 1899, the building was completed by his son Thomas Manly Deane.