The association of Brown Windsor soup with Queen Victoria is attributed by Wikipedia to a blog entitled The Old Foodie, according to which "The generally accepted explanation is that the Windsor Soup loved yet despised by the Victorian English evolved from Calves Feet Soup à la Windsor, created by her chef Charles Elmé Francatelli for the newly post–natal Queen Victoria." Wikipedia also cites a website called Genius Kitchen, which (if I'm not mistaken) is the source of the recipe summarised in the question.
According to Wikipedia, 'The earliest known cases of "Brown Windsor soup" are found in restaurant menus published as advertisements in newspapers during the 1920s and 1930s.' Wikipedia goes on to summarise the conclusions of Michael Quinlon on the excellent World Wide Words website, the essence of which is that there was once a white Windsor soup and a brown Windsor soap, and the two probably became conflated as brown Windsor soup.
Brown Windsor soup has long been a byword for awful British food, and has been mentioned as such in (among others) two Carry On films, The Goon Show, Hancock's Half Hour, Fawlty Towers, John Mortimer's Rumpole stories, and the Hercule Poirot mysteries of Agatha Christie.
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