Walter Armstrong was a writer, art critic and gallery director. He was the only son of Walter Armstrong, a wealthy man. He had three sisters, Mrs Tennant Dunlop, Mrs Secker and Mrs Ponsonby Blennerhassett, who appear in John Everett Millais' Hearts are Trumps. He married Emily Rose Ferard.
Armstrong was educated at Exeter College, Oxford. He began his literary career contributing to the English Illustrated Magazine, edited by Comyns Carr. He also contributed to the Magazine of Art, edited by M. H. Spielmann. From 1880 to 1892 he was an art critic for the Pall Mall Gazette, edited by Frederick Greenwood, as well as for the Manchester Guardian, St James's Gazette and Guardian.
According to Spielman, who called JW 'that arch criticomastix', Armstrong had little liking for JW the man, aside from his art. In response to an unsigned article 'Mr Whistler's Venice' which appeared in the St James's Gazette in December 1880, JW described Armstrong as 'a foolish gentleman' (#07127). In Etchings & Drypoints. Venice. Second Series, the exhibition catalogue for Mr Whistler's Etchings, The Fine Art Society, London, 1883, JW quoted liberally and mockingly from the St James's Gazette.
Armstrong, however, published critical monographs on a number of artists greatly admired by JW, including Velásquez (1897), Thomas Gainsborough (1898) and Alfred Stevens (1881), as well as volumes on such major figures as W. Q. Orchardson (1895), Sir Joshua Reynolds (1900), Sir Henry Raeburn (1901), J. M. W. Turner (1901-2), William Hogarth (1902) and Sir Thomas Lawrence (1913). Further publications include The Thames from its Rise to the Nore (1884), Scottish Painters (1888), volume two of Bryan's Dictionary of Painters and Engravers (1889), Art in Great Britain and Ireland (1909). He also wrote introductions to the catalogues of the Burlington Fine Arts Club exhibitions of Pictures of Early Netherlandish and the Allied Schools (1892) and Pictures by Dutch Masters of the 17th Century (1900).
He became Director of the National Gallery of Ireland in 1892, succeeding Henry E. Doyle.
Portraits of Armstrong were carried out in bronze by E. Onslow Ford and in oils by Walter Osborne. The latter was praised by JW who exclaimed while standing in front of it: 'It has a skin! It has a skin!' This latter comment was made during a visit to Dublin in 1900, when Armstrong accompanied him around the National Gallery. JW also had dinner with him on this occasion and Armstrong told Pennell of the 'delightful flow of Whistler's eloquence' that evening, describing his armchair as JW's 'pulpit'.
Who's Who, 1898, London, 1898; Pennell, Elizabeth Robins, and Joseph Pennell, The Life of James McNeill Whistler, 2 vols, London and Philadelphia, 1908; Spielmann, Marion Harry, 'Sir Walter Armstrong', Fortnightly Review, n.s., vol. 104, 1918, pp. 934-47.