THE ROYAL WU: On Friday afternoon at Jason Wu’s spring runway show at Manhattan’s St. John’s Center, Emily Mortimer was reminiscing about her brush with Japanese royalty. A few years back the English actress, who has had plenty of exposure Stateside lately care of Aaron Sorkin’s “The Newsroom,” had worn a Wu dress to the premiere of a film in Tokyo. “He dressed me in this beautiful sort of silk, almost like 1930s bias cut evening gown that was black and white,” she said in her boisterous British lilt. “I sat next to the empress of Japan, which is a very rare thing because she never leaves her house. She’s the most elegant lady I’ve ever met. Old.. I don’t know how old, an elegant old lady! And she just loved my dress and kept asking me about it and touching it and saying, ‘Who made this dress?’ So I knew I was onto a good thing.” Other front row attendees onto the same good thing included Harley Viera-Newton, the Courtin Clarins clique, China Chow and Shala Monroque.