A prominant London couture atelier in the Jazz Age was that of Jean-Philippe based originally at 39 Conduit street, W1, which thrived through the 1920s and into the 1930s. Jean-Philippe was owned and run by the society hostess Mrs Simon Hartog and since the first known listing in the press was in late 1926, one must presume that the establishment was formed in or around 1926.
