Butterfield produced a notable example of Victorian Gothic architecture, among his few secular buildings, which Pevsner characterised as "actively ugly", and which, according to Charles Eastlake, defied criticism. The social historian G. M. Trevelyan expressed the then commonly held, and highly dismissive, view; "the monstrosities of architecture erected by order of the dons of Oxford and Cambridge colleges in the days of William Butterfield and Alfred Waterhouse give daily pain to posterity." Sir Kenneth Clark recalled that during his Oxford years it was generally believed in Oxford not only that Keble College was "the ugliest building in the world" but that its architect was John Ruskin, author of "The Stones of Venice." The college is built of red, blue, and white bricks; the main structure is of red brick, with white and blue patterned banding. The builders were Parnell & Son of Rugby.