The English and the French have traditionally disagreed about many things, each convinced that their point of view makes more sense: dandyism is no exception.
Edward Bulwer-Lytton: English dandy and author of Pelham
When dandyism first began, it began in England. A well placed commoner gained a sort of virtual control of the country by his impeccable yet simple dress, fine manners and impertinent attitude, he reign until the powers who were supposed to rule could no longer take the weight of Brummel's absolute monarchy. Dandyism started in England, and according Barbey d'Aurevilly, it will stay there. Well the French themselves did not agree, and very quickly dandyism moved across the "The Channel" and began to appear in France- it was in fact Brummel who brought it there. The French loved dandyism, and its effect on the streets of Paris was at least as great as its influence in London. However French dandyism was different: as different as France is from England. For the French dandyism meant refinement- and they loved refinement. The dandy meant attitude, beauty, insolence, and a sniff of decadence...for the French of the age, a better definition of their piece of the European continent could not have been drawn by any cartographer. "It was when French social distinctions blurred in the 1830s that dandyism emerged as an oppositional mode. If Louis-Philippe and his court endorsed the "vulgar" bourgeois work ethic, the dandy[...] embraced a program of ostentatious idleness and gratification*. There were several who followed Brummel's example in France. Each one uniquely dandy in their own right, and also uniquely French. The best example I can think of of a French "dandy" who fits perfectly into the French mold, and not at all into the English one is Jean Lorrain. An effete man [and openly gay- unusual for the period], He was huge devotée of dandyism and wrote a number of works including La Foret Bleue, L'ombre Ardente, and especially M. de Phocas.
On the English side this effete man who delighted in writing rich, descriptive, and often scandalous novels was quite a bit removed from the ideal that "Beau" Brummel had inspired. Much closer to the mark was Sir. Edward Bulwer-Lytton. A baronet, a man of certain sobriety, highly active in politics, and a writer of some renown, his greatest achievement in the world of dandyism is his novel "Pelham: adventures of a gentlemen" which chronicles the adventures of a young dandy, and set not a few standard including the rule on only black and white for formal evening wear.
These two sides of dandyism would battle for supremacy through out the 19th Century. Several notable figures would emerge to sway the balance one way or another and this tend would continue as Robert de Montesquiou would replace Jean Lorrain in France, and Max Beerbohm replaced Lord Lytton in England as the most popular example of dandyism , still following along the same trend of the great divide. The French would continue to produce dandies who reveled in opulence, drank absinthe, smoked opium and dreamed of the better world that was; and really finally died to become the chic artist for which France is so well known. The English dandy on the other hand stayed more sober, pursued his elegance in keeping with the time, and became the Duke of Windsor who would cast all responsibility aside to remain a playboy.
Dandyism also came to America and would be seen in the likes of Fred Astaire, Gary Cooper and the like, and would eventually eclipse the English [at least on the popular stage] but that is a treatise for another page ;-]
Jean Lorrain: French dandy and author of M. de Phocas
*[J. Hoberman Village Voice movie review of Last Mistress]