Pippa Middleton’s big day won’t have the pomp and circumstance of a royal affair. Duchess Kate’s younger sister, 33, who will wed her fiancé, financier James Matthews, May 20, is keeping the event “classic and elegant,” says an insider. “She doesn’t want it to be too expensive or look gaudy.” The socialite and 41-year-old London resident Matthews — together off and on since 2012 — will marry at St Mark’s Englefield, a picturesque stone church built in the 12th century, near her parents’ home in Berkshire, England. While Kate’s daughter, Charlotte, 23months, and son, George, 3, will serve as bridesmaid and page boy, respectively, Kate won’t have an official role or even do a reading at the church. “The sisters,” explains a source, “don’t want it to turn into a…
