This is somewhat obscure, but the consensus of my more knowledgeable friends (140, 243, 247, 251, 265, 273) is that the reference is to the bohemian inhabitants of that part of London. Quoting Prestige (243): "South Kensington was, and still is, the centre in London for art museums, the Royal College of Art, and the area where those so inclined live or (if students) lodge. Punch of the period made frequent references to the outré aesthetic habits of the denizens of South Kensington." Rees (251) makes these comments: "South Kensington and the immediately adjacent Brompton were not only the sites of more than one 'art school' but also the abode of many of the more aesthetically inclined. Gilbert lived on the fringe of this area at The Boltons during the 1870s and '80s and it was here that he wrote the libretto of Patience … Aesthetes were probably two-a-penny in some of the streets nearby and Gilbert doubtless had plenty of opportunity to study them in situ." The aesthetes of that day would certainly look upon primary colors as lacking in sophistication. To Jane's "Oh, South Kensington!" might be added: "Forgive these hopeless Philistines."